Convert digits into words with JavaScript


I am making a code which converts the given amount into words, heres is what I have got after googling. But I think its a little lengthy code to achieve a simple task. Two Regular Expressions and two for loops, I want something simpler.

I am trying to make it as shorter as possible. and will post what I come up with

Any suggestions?

var th = ['','thousand','million', 'billion','trillion'];
var dg = ['zero','one','two','three','four', 'five','six','seven','eight','nine'];
 var tn = ['ten','eleven','twelve','thirteen', 'fourteen','fifteen','sixteen', 'seventeen','eighteen','nineteen'];
 var tw = ['twenty','thirty','forty','fifty', 'sixty','seventy','eighty','ninety'];

function toWords(s) {
    s = s.toString();
    s = s.replace(/[\, ]/g,'');
    if (s != parseFloat(s)) return 'not a number';
    var x = s.indexOf('.');
    if (x == -1)
        x = s.length;
    if (x > 15)
        return 'too big';
    var n = s.split(''); 
    var str = '';
    var sk = 0;
    for (var i=0;   i < x;  i++) {
        if ((x-i)%3==2) { 
            if (n[i] == '1') {
                str += tn[Number(n[i+1])] + ' ';
                i++;
                sk=1;
            } else if (n[i]!=0) {
                str += tw[n[i]-2] + ' ';
                sk=1;
            }
        } else if (n[i]!=0) { // 0235
            str += dg[n[i]] +' ';
            if ((x-i)%3==0) str += 'hundred ';
            sk=1;
        }
        if ((x-i)%3==1) {
            if (sk)
                str += th[(x-i-1)/3] + ' ';
            sk=0;
        }
    }

    if (x != s.length) {
        var y = s.length;
        str += 'point ';
        for (var i=x+1; i<y; i++)
            str += dg[n[i]] +' ';
    }
    return str.replace(/\s+/g,' ');
}

Also, the above code converts to English numbering system like Million/Billion, I wan't South Asian numbering system. like in Lakhs and Crores

Update: Looks like this is more useful than I thought. I've just published this on npm. https://www.npmjs.com/package/num-words


Here's a shorter code. with one RegEx and no loops. converts as you wanted, in south asian numbering system

var a = ['','one ','two ','three ','four ', 'five ','six ','seven ','eight ','nine ','ten ','eleven ','twelve ','thirteen ','fourteen ','fifteen ','sixteen ','seventeen ','eighteen ','nineteen '];
var b = ['', '', 'twenty','thirty','forty','fifty', 'sixty','seventy','eighty','ninety'];

function inWords (num) {
    if ((num = num.toString()).length > 9) return 'overflow';
    n = ('000000000' + num).substr(-9).match(/^(\d{2})(\d{2})(\d{2})(\d{1})(\d{2})$/);
    if (!n) return; var str = '';
    str += (n[1] != 0) ? (a[Number(n[1])] || b[n[1][0]] + ' ' + a[n[1][1]]) + 'crore ' : '';
    str += (n[2] != 0) ? (a[Number(n[2])] || b[n[2][0]] + ' ' + a[n[2][1]]) + 'lakh ' : '';
    str += (n[3] != 0) ? (a[Number(n[3])] || b[n[3][0]] + ' ' + a[n[3][1]]) + 'thousand ' : '';
    str += (n[4] != 0) ? (a[Number(n[4])] || b[n[4][0]] + ' ' + a[n[4][1]]) + 'hundred ' : '';
    str += (n[5] != 0) ? ((str != '') ? 'and ' : '') + (a[Number(n[5])] || b[n[5][0]] + ' ' + a[n[5][1]]) + 'only ' : '';
    return str;
}

document.getElementById('number').onkeyup = function () {
    document.getElementById('words').innerHTML = inWords(document.getElementById('number').value);
};
<span id="words"></span>
<input id="number" type="text" />

The only limitation is, you can convert maximum of 9 digits, which I think is more than sufficient in most cases..


"Deceptively simple task." – Potatoswatter

Indeed. There's many little devils hanging out in the details of this problem. It was very fun to solve tho.

EDIT: This update takes a much more compositional approach. Previously there was one big function which wrapped a couple other proprietary functions. Instead, this time we define generic reusable functions which could be used for many varieties of tasks. More about those after we take a look at numToWords itself …

// numToWords :: (Number a, String a) => a -> String
let numToWords = n => {
  let a = [
    '', 'one', 'two', 'three', 'four',
    'five', 'six', 'seven', 'eight', 'nine',
    'ten', 'eleven', 'twelve', 'thirteen', 'fourteen',
    'fifteen', 'sixteen', 'seventeen', 'eighteen', 'nineteen'
  ];
  let b = [
    '', '', 'twenty', 'thirty', 'forty',
    'fifty', 'sixty', 'seventy', 'eighty', 'ninety'
  ];
  let g = [
    '', 'thousand', 'million', 'billion', 'trillion', 'quadrillion',
    'quintillion', 'sextillion', 'septillion', 'octillion', 'nonillion'
  ];
  // this part is really nasty still
  // it might edit this again later to show how Monoids could fix this up
  let makeGroup = ([ones,tens,huns]) => {
    return [
      num(huns) === 0 ? '' : a[huns] + ' hundred ',
      num(ones) === 0 ? b[tens] : b[tens] && b[tens] + '-' || '',
      a[tens+ones] || a[ones]
    ].join('');
  };
  // "thousands" constructor; no real good names for this, i guess
  let thousand = (group,i) => group === '' ? group : `${group} ${g[i]}`;
  // execute !
  if (typeof n === 'number') return numToWords(String(n));
  if (n === '0')             return 'zero';
  return comp (chunk(3)) (reverse) (arr(n))
    .map(makeGroup)
    .map(thousand)
    .filter(comp(not)(isEmpty))
    .reverse()
    .join(' ');
};

Here are the dependencies:

You'll notice these require next to no documentation because their intents are immediately clear. chunk might be the only one that takes a moment to digest, but it's really not too bad. Plus the function name gives us a pretty good indication what it does, and it's probably a function we've encountered before.

const arr = x => Array.from(x);
const num = x => Number(x) || 0;
const str = x => String(x);
const isEmpty = xs => xs.length === 0;
const take = n => xs => xs.slice(0,n);
const drop = n => xs => xs.slice(n);
const reverse = xs => xs.slice(0).reverse();
const comp = f => g => x => f (g (x));
const not = x => !x;
const chunk = n => xs =>
  isEmpty(xs) ? [] : [take(n)(xs), ...chunk (n) (drop (n) (xs))];

"So these make it better?"

Look at how the code has cleaned up significantly

// NEW CODE (truncated)
return comp (chunk(3)) (reverse) (arr(n))
    .map(makeGroup)
    .map(thousand)
    .filter(comp(not)(isEmpty))
    .reverse()
    .join(' ');

// OLD CODE (truncated)
let grp = n => ('000' + n).substr(-3);
let rem = n => n.substr(0, n.length - 3);
let cons = xs => x => g => x ? [x, g && ' ' + g || '', ' ', xs].join('') : xs;
let iter = str => i => x => r => {
  if (x === '000' && r.length === 0) return str;
  return iter(cons(str)(fmt(x))(g[i]))
             (i+1)
             (grp(r))
             (rem(r));
};
return iter('')(0)(grp(String(n)))(rem(String(n)));

Most importantly, the utility functions we added in the new code can be used other places in your app. This means that, as a side effect of implementing numToWords in this way, we get the other functions for free. Bonus soda !

Some tests

console.log(numToWords(11009));
//=> eleven thousand nine

console.log(numToWords(10000001));
//=> ten million one 

console.log(numToWords(987));
//=> nine hundred eighty-seven

console.log(numToWords(1015));
//=> one thousand fifteen

console.log(numToWords(55111222333));
//=> fifty-five billion one hundred eleven million two hundred 
//   twenty-two thousand three hundred thirty-three

console.log(numToWords("999999999999999999999991"));
//=> nine hundred ninety-nine sextillion nine hundred ninety-nine
//   quintillion nine hundred ninety-nine quadrillion nine hundred
//   ninety-nine trillion nine hundred ninety-nine billion nine
//   hundred ninety-nine million nine hundred ninety-nine thousand
//   nine hundred ninety-one

console.log(numToWords(6000753512));
//=> six billion seven hundred fifty-three thousand five hundred
//   twelve 

Runnable demo

const arr = x => Array.from(x);
const num = x => Number(x) || 0;
const str = x => String(x);
const isEmpty = xs => xs.length === 0;
const take = n => xs => xs.slice(0,n);
const drop = n => xs => xs.slice(n);
const reverse = xs => xs.slice(0).reverse();
const comp = f => g => x => f (g (x));
const not = x => !x;
const chunk = n => xs =>
  isEmpty(xs) ? [] : [take(n)(xs), ...chunk (n) (drop (n) (xs))];

// numToWords :: (Number a, String a) => a -> String
let numToWords = n => {
  
  let a = [
    '', 'one', 'two', 'three', 'four',
    'five', 'six', 'seven', 'eight', 'nine',
    'ten', 'eleven', 'twelve', 'thirteen', 'fourteen',
    'fifteen', 'sixteen', 'seventeen', 'eighteen', 'nineteen'
  ];
  
  let b = [
    '', '', 'twenty', 'thirty', 'forty',
    'fifty', 'sixty', 'seventy', 'eighty', 'ninety'
  ];
  
  let g = [
    '', 'thousand', 'million', 'billion', 'trillion', 'quadrillion',
    'quintillion', 'sextillion', 'septillion', 'octillion', 'nonillion'
  ];
  
  // this part is really nasty still
  // it might edit this again later to show how Monoids could fix this up
  let makeGroup = ([ones,tens,huns]) => {
    return [
      num(huns) === 0 ? '' : a[huns] + ' hundred ',
      num(ones) === 0 ? b[tens] : b[tens] && b[tens] + '-' || '',
      a[tens+ones] || a[ones]
    ].join('');
  };
  
  let thousand = (group,i) => group === '' ? group : `${group} ${g[i]}`;
  
  if (typeof n === 'number')
    return numToWords(String(n));
  else if (n === '0')
    return 'zero';
  else
    return comp (chunk(3)) (reverse) (arr(n))
      .map(makeGroup)
      .map(thousand)
      .filter(comp(not)(isEmpty))
      .reverse()
      .join(' ');
};


console.log(numToWords(11009));
//=> eleven thousand nine

console.log(numToWords(10000001));
//=> ten million one 

console.log(numToWords(987));
//=> nine hundred eighty-seven

console.log(numToWords(1015));
//=> one thousand fifteen

console.log(numToWords(55111222333));
//=> fifty-five billion one hundred eleven million two hundred 
//   twenty-two thousand three hundred thirty-three

console.log(numToWords("999999999999999999999991"));
//=> nine hundred ninety-nine sextillion nine hundred ninety-nine
//   quintillion nine hundred ninety-nine quadrillion nine hundred
//   ninety-nine trillion nine hundred ninety-nine billion nine
//   hundred ninety-nine million nine hundred ninety-nine thousand
//   nine hundred ninety-one

console.log(numToWords(6000753512));
//=> six billion seven hundred fifty-three thousand five hundred
//   twelve


You can transpile the code using babel.js if you want to see the ES5 variant


I spent a while developing a better solution to this. It can handle very big numbers but once they get over 16 digits you have pass the number in as a string. Something about the limit of JavaScript numbers.

	function numberToEnglish( n ) {
		
		var string = n.toString(), units, tens, scales, start, end, chunks, chunksLen, chunk, ints, i, word, words, and = 'and';

		/* Remove spaces and commas */
		string = string.replace(/[, ]/g,"");

		/* Is number zero? */
		if( parseInt( string ) === 0 ) {
			return 'zero';
		}
		
		/* Array of units as words */
		units = [ '', 'one', 'two', 'three', 'four', 'five', 'six', 'seven', 'eight', 'nine', 'ten', 'eleven', 'twelve', 'thirteen', 'fourteen', 'fifteen', 'sixteen', 'seventeen', 'eighteen', 'nineteen' ];
		
		/* Array of tens as words */
		tens = [ '', '', 'twenty', 'thirty', 'forty', 'fifty', 'sixty', 'seventy', 'eighty', 'ninety' ];
		
		/* Array of scales as words */
		scales = [ '', 'thousand', 'million', 'billion', 'trillion', 'quadrillion', 'quintillion', 'sextillion', 'septillion', 'octillion', 'nonillion', 'decillion', 'undecillion', 'duodecillion', 'tredecillion', 'quatttuor-decillion', 'quindecillion', 'sexdecillion', 'septen-decillion', 'octodecillion', 'novemdecillion', 'vigintillion', 'centillion' ];
		
		/* Split user arguemnt into 3 digit chunks from right to left */
		start = string.length;
		chunks = [];
		while( start > 0 ) {
			end = start;
			chunks.push( string.slice( ( start = Math.max( 0, start - 3 ) ), end ) );
		}
		
		/* Check if function has enough scale words to be able to stringify the user argument */
		chunksLen = chunks.length;
		if( chunksLen > scales.length ) {
			return '';
		}
		
		/* Stringify each integer in each chunk */
		words = [];
		for( i = 0; i < chunksLen; i++ ) {
			
			chunk = parseInt( chunks[i] );
			
			if( chunk ) {
				
				/* Split chunk into array of individual integers */
				ints = chunks[i].split( '' ).reverse().map( parseFloat );
			
				/* If tens integer is 1, i.e. 10, then add 10 to units integer */
				if( ints[1] === 1 ) {
					ints[0] += 10;
				}
				
				/* Add scale word if chunk is not zero and array item exists */
				if( ( word = scales[i] ) ) {
					words.push( word );
				}
				
				/* Add unit word if array item exists */
				if( ( word = units[ ints[0] ] ) ) {
					words.push( word );
				}
				
				/* Add tens word if array item exists */
				if( ( word = tens[ ints[1] ] ) ) {
					words.push( word );
				}
				
				/* Add 'and' string after units or tens integer if: */
				if( ints[0] || ints[1] ) {
					
					/* Chunk has a hundreds integer or chunk is the first of multiple chunks */
					if( ints[2] || ! i && chunksLen ) {
						words.push( and );
					}
				
				}
				
				/* Add hundreds word if array item exists */
				if( ( word = units[ ints[2] ] ) ) {
					words.push( word + ' hundred' );
				}
				
			}
			
		}
		
		return words.reverse().join( ' ' );
		
	}


// - - - - - Tests - - - - - -
function test(v) {
  var sep = ('string'==typeof v)?'"':'';
  console.log("numberToEnglish("+sep + v.toString() + sep+") = "+numberToEnglish(v));
}
test(2);
test(721);
test(13463);
test(1000001);
test("21,683,200,000,621,384");


You might want to try it recursive. It works for numbers between 0 and 999999. Keep in mind that (~~) does the same as Math.floor

var num = "zero one two three four five six seven eight nine ten eleven twelve thirteen fourteen fifteen sixteen seventeen eighteen nineteen".split(" ");
var tens = "twenty thirty forty fifty sixty seventy eighty ninety".split(" ");

function number2words(n){
    if (n < 20) return num[n];
    var digit = n%10;
    if (n < 100) return tens[~~(n/10)-2] + (digit? "-" + num[digit]: "");
    if (n < 1000) return num[~~(n/100)] +" hundred" + (n%100 == 0? "": " " + number2words(n%100));
    return number2words(~~(n/1000)) + " thousand" + (n%1000 != 0? " " + number2words(n%1000): "");
}


enter image description here

 <html>

<head>

    <title>HTML - Convert numbers to words using JavaScript</title>

    <script  type="text/javascript">
    	function onlyNumbers(evt) {
    var e = event || evt; // For trans-browser compatibility
    var charCode = e.which || e.keyCode;

    if (charCode > 31 && (charCode < 48 || charCode > 57))
        return false;
    return true;
}

function NumToWord(inputNumber, outputControl) {
    var str = new String(inputNumber)
    var splt = str.split("");
    var rev = splt.reverse();
    var once = ['Zero', ' One', ' Two', ' Three', ' Four', ' Five', ' Six', ' Seven', ' Eight', ' Nine'];
    var twos = ['Ten', ' Eleven', ' Twelve', ' Thirteen', ' Fourteen', ' Fifteen', ' Sixteen', ' Seventeen', ' Eighteen', ' Nineteen'];
    var tens = ['', 'Ten', ' Twenty', ' Thirty', ' Forty', ' Fifty', ' Sixty', ' Seventy', ' Eighty', ' Ninety'];

    numLength = rev.length;
    var word = new Array();
    var j = 0;

    for (i = 0; i < numLength; i++) {
        switch (i) {

            case 0:
                if ((rev[i] == 0) || (rev[i + 1] == 1)) {
                    word[j] = '';
                }
                else {
                    word[j] = '' + once[rev[i]];
                }
                word[j] = word[j];
                break;

            case 1:
                aboveTens();
                break;

            case 2:
                if (rev[i] == 0) {
                    word[j] = '';
                }
                else if ((rev[i - 1] == 0) || (rev[i - 2] == 0)) {
                    word[j] = once[rev[i]] + " Hundred ";
                }
                else {
                    word[j] = once[rev[i]] + " Hundred and";
                }
                break;

            case 3:
                if (rev[i] == 0 || rev[i + 1] == 1) {
                    word[j] = '';
                }
                else {
                    word[j] = once[rev[i]];
                }
                if ((rev[i + 1] != 0) || (rev[i] > 0)) {
                    word[j] = word[j] + " Thousand";
                }
                break;

                
            case 4:
                aboveTens();
                break;

            case 5:
                if ((rev[i] == 0) || (rev[i + 1] == 1)) {
                    word[j] = '';
                }
                else {
                    word[j] = once[rev[i]];
                }
                if (rev[i + 1] !== '0' || rev[i] > '0') {
                    word[j] = word[j] + " Lakh";
                }
                 
                break;

            case 6:
                aboveTens();
                break;

            case 7:
                if ((rev[i] == 0) || (rev[i + 1] == 1)) {
                    word[j] = '';
                }
                else {
                    word[j] = once[rev[i]];
                }
                if (rev[i + 1] !== '0' || rev[i] > '0') {
                    word[j] = word[j] + " Crore";
                }                
                break;

            case 8:
                aboveTens();
                break;

            //            This is optional. 

            //            case 9:
            //                if ((rev[i] == 0) || (rev[i + 1] == 1)) {
            //                    word[j] = '';
            //                }
            //                else {
            //                    word[j] = once[rev[i]];
            //                }
            //                if (rev[i + 1] !== '0' || rev[i] > '0') {
            //                    word[j] = word[j] + " Arab";
            //                }
            //                break;

            //            case 10:
            //                aboveTens();
            //                break;

            default: break;
        }
        j++;
    }

    function aboveTens() {
        if (rev[i] == 0) { word[j] = ''; }
        else if (rev[i] == 1) { word[j] = twos[rev[i - 1]]; }
        else { word[j] = tens[rev[i]]; }
    }

    word.reverse();
    var finalOutput = '';
    for (i = 0; i < numLength; i++) {
        finalOutput = finalOutput + word[i];
    }
    document.getElementById(outputControl).innerHTML = finalOutput;
}
    </script>

</head>

<body>

    <h1>

        HTML - Convert numbers to words using JavaScript</h1>

    <input id="Text1" type="text" onkeypress="return onlyNumbers(this.value);" onkeyup="NumToWord(this.value,'divDisplayWords');"

        maxlength="9" style="background-color: #efefef; border: 2px solid #CCCCC; font-size: large" />

    <br />

    <br />

    <div id="divDisplayWords" style="font-size: 13; color: Teal; font-family: Arial;">

    </div>

</body>

</html>


I like the result I got here which i think is easy to read and short enough to fit as a solution.

function NumInWords (number) {
  const first = ['','one ','two ','three ','four ', 'five ','six ','seven ','eight ','nine ','ten ','eleven ','twelve ','thirteen ','fourteen ','fifteen ','sixteen ','seventeen ','eighteen ','nineteen '];
  const tens = ['', '', 'twenty','thirty','forty','fifty', 'sixty','seventy','eighty','ninety'];
  const mad = ['', 'thousand', 'million', 'billion', 'trillion'];
  let word = '';

  for (let i = 0; i < mad.length; i++) {
    let tempNumber = number%(100*Math.pow(1000,i));
    if (Math.floor(tempNumber/Math.pow(1000,i)) !== 0) {
      if (Math.floor(tempNumber/Math.pow(1000,i)) < 20) {
        word = first[Math.floor(tempNumber/Math.pow(1000,i))] + mad[i] + ' ' + word;
      } else {
        word = tens[Math.floor(tempNumber/(10*Math.pow(1000,i)))] + '-' + first[Math.floor(tempNumber/Math.pow(1000,i))%10] + mad[i] + ' ' + word;
      }
    }

    tempNumber = number%(Math.pow(1000,i+1));
    if (Math.floor(tempNumber/(100*Math.pow(1000,i))) !== 0) word = first[Math.floor(tempNumber/(100*Math.pow(1000,i)))] + 'hunderd ' + word;
  }
    return word;
}

console.log(NumInWords(89754697976431))

And the result is :

eighty-nine trillion seven hundred fifty-four billion six hundred ninety-seven million nine hundred seventy-six thousand four hundred thirty-one


Converting the input string into a number rather than keeping it as a string, limits the solution to the maximum allowed float / integer value on that machine/browser. My script below handles currency up to 1 Trillion dollars - 1 cent :-). I can be extended to handle up to 999 Trillions by adding 3 or 4 lines of code.

var ones = ["","One","Two","Three","Four","Five","Six","Seven","Eight",
            "Nine","Ten","Eleven","Twelve","Thirteen","Fourteen",
            "Fifteen","Sixteen","Seventeen","Eighteen","Nineteen"]; 

var tens = ["","","Twenty","Thirty","Forty","Fifty","Sixty","Seventy",
            "Eighty","Ninety"]; 


function words999(n999)   {    // n999 is an integer less than or equal to 999.
//
// Accept any 3 digit int incl 000 & 999 and return words.
// 

    var words = ''; var Hn = 0; var n99 = 0;

    Hn = Math.floor(n999 / 100);                  // # of hundreds in it

    if (Hn > 0)   {                               // if at least one 100

      words = words99(Hn) + " Hundred";           // one call for hundreds
    }

    n99 = n999 - (Hn * 100);                      // subtract the hundreds.

    words += ((words == '')?'':' ') + words99(n99); // combine the hundreds with tens & ones.

    return words;
}                            // function words999( n999 )

function words99(n99)   {    // n99 is an integer less than or equal to 99.
//
// Accept any 2 digit int incl 00 & 99 and return words.
// 

    var words = ''; var Dn = 0; var Un = 0;

    Dn = Math.floor(n99 / 10);           // # of tens

    Un = n99 % 10;                       // units

    if (Dn > 0 || Un > 0) {

      if (Dn < 2) {

        words += ones[Dn * 10 + Un];     // words for a # < 20

      } else {

        words += tens[Dn];

        if (Un > 0) words += "-" + ones[Un];
      }
    }                               // if ( Dn > 0 || Un > 0 )

    return words;
}                                   // function words99( n99 )

function getAmtInWords(id1, id2) {  // use numeric value of id1 to populate text in id2 
//
// Read numeric amount field and convert into word amount
// 

    var t1 = document.getElementById(id1).value;

    var t2 = t1.trim();

    amtStr = t2.replace(/,/g,'');        // $123,456,789.12 = 123456789.12

    dotPos = amtStr.indexOf('.');        // position of dot before cents, -ve if it doesn't exist.

    if (dotPos > 0) {

      dollars = amtStr.slice(0,dotPos);  // 1234.56 = 1234
      cents   = amtStr.slice(dotPos+1);  // 1234.56 = .56

    } else if (dotPos == 0) {

      dollars = '0';
      cents   = amtStr.slice(dotPos+1);  // 1234.56 = .56

    } else {

      dollars = amtStr.slice(0);         // 1234 = 1234
      cents   = '0'; 
    }

    t1      = '000000000000' + dollars;  // to extend to trillion, use 15 zeros
    dollars =  t1.slice(-12);            // and -15 here.

    billions  = Number(dollars.substr(0,3));
    millions  = Number(dollars.substr(3,3));
    thousands = Number(dollars.substr(6,3));
    hundreds  = Number(dollars.substr(9,3));

    t1 = words999(billions);    bW = t1.trim();   // Billions  in words

    t1 = words999(millions);    mW = t1.trim();   // Millions  in words

    t1 = words999(thousands);   tW = t1.trim();   // Thousands in words

    t1 = words999(hundreds);    hW = t1.trim();   // Hundreds  in words

    t1 = words99(cents);        cW = t1.trim();   // Cents     in words

    var totAmt = '';

    if (bW != '')   totAmt += ((totAmt != '') ? ' '  : '') + bW + ' Billion';
    if (mW != '')   totAmt += ((totAmt != '') ? ' '  : '') + mW + ' Million';
    if (tW != '')   totAmt += ((totAmt != '') ? ' '  : '') + tW + ' Thousand';
    if (hW != '')   totAmt += ((totAmt != '') ? ' '  : '') + hW + ' Dollars';

    if (cW != '')   totAmt += ((totAmt != '') ? ' and ' : '') + cW + ' Cents';

//  alert('totAmt = ' + totAmt);    // display words in a alert

    t1 = document.getElementById(id2).value;

    t2 = t1.trim();

    if (t2 == '')  document.getElementById(id2).value = totAmt;

    return false;
}                        // function getAmtInWords( id1, id2 )

// ======================== [ End Code ] ====================================

This is in response to @LordZardeck's comment to @naomik's excellent answer above. Sorry, I would've commented directly but I've never posted before so I don't have the privilege to do so, so I am posting here instead.

Anyhow, I just happened to translate the ES5 version to a more readable form this past weekend so I'm sharing it here. This should be faithful to the original (including the recent edit) and I hope the naming is clear and accurate.

function int_to_words(int) {
  if (int === 0) return 'zero';

  var ONES  = ['','one','two','three','four','five','six','seven','eight','nine','ten','eleven','twelve','thirteen','fourteen','fifteen','sixteen','seventeen','eighteen','nineteen'];
  var TENS  = ['','','twenty','thirty','fourty','fifty','sixty','seventy','eighty','ninety'];
  var SCALE = ['','thousand','million','billion','trillion','quadrillion','quintillion','sextillion','septillion','octillion','nonillion'];

  // Return string of first three digits, padded with zeros if needed
  function get_first(str) {
    return ('000' + str).substr(-3);
  }

  // Return string of digits with first three digits chopped off
  function get_rest(str) {
    return str.substr(0, str.length - 3);
  }

  // Return string of triplet convereted to words
  function triplet_to_words(_3rd, _2nd, _1st) {
    return (_3rd == '0' ? '' : ONES[_3rd] + ' hundred ') + (_1st == '0' ? TENS[_2nd] : TENS[_2nd] && TENS[_2nd] + '-' || '') + (ONES[_2nd + _1st] || ONES[_1st]);
  }

  // Add to words, triplet words with scale word
  function add_to_words(words, triplet_words, scale_word) {
    return triplet_words ? triplet_words + (scale_word && ' ' + scale_word || '') + ' ' + words : words;
  }

  function iter(words, i, first, rest) {
    if (first == '000' && rest.length === 0) return words;
    return iter(add_to_words(words, triplet_to_words(first[0], first[1], first[2]), SCALE[i]), ++i, get_first(rest), get_rest(rest));
  }

  return iter('', 0, get_first(String(int)), get_rest(String(int)));
}

If you need with Cent then you may use this one

        <script>
            var iWords = ['zero', ' one', ' two', ' three', ' four', ' five', ' six', ' seven', ' eight', ' nine'];
            var ePlace = ['ten', ' eleven', ' twelve', ' thirteen', ' fourteen', ' fifteen', ' sixteen', ' seventeen', ' eighteen', ' nineteen'];
            var tensPlace = ['', ' ten', ' twenty', ' thirty', ' forty', ' fifty', ' sixty', ' seventy', ' eighty', ' ninety'];
            var inWords = [];

            var numReversed, inWords, actnumber, i, j;

            function tensComplication() {
            if (actnumber[i] == 0) {
                inWords[j] = '';
            } else if (actnumber[i] == 1) {
                inWords[j] = ePlace[actnumber[i - 1]];
            } else {
                inWords[j] = tensPlace[actnumber[i]];
            }
            }

            function convertAmount() {
                var numericValue = document.getElementById('bdt').value;
                numericValue = parseFloat(numericValue).toFixed(2);

                var amount = numericValue.toString().split('.');
                var taka = amount[0];
                var paisa = amount[1];
                document.getElementById('container').innerHTML = convert(taka) +" taka and "+ convert(paisa)+" paisa only";
            }
            function convert(numericValue) {
            inWords = []
            if(numericValue == "00" || numericValue =="0"){
                return 'zero';
            }
            var obStr = numericValue.toString();
            numReversed = obStr.split('');
            actnumber = numReversed.reverse();


            if (Number(numericValue) == 0) {
                document.getElementById('container').innerHTML = 'BDT Zero';
                return false;
            }

            var iWordsLength = numReversed.length;
            var finalWord = '';
            j = 0;
            for (i = 0; i < iWordsLength; i++) {
                switch (i) {
                    case 0:
                        if (actnumber[i] == '0' || actnumber[i + 1] == '1') {
                            inWords[j] = '';
                        } else {
                            inWords[j] = iWords[actnumber[i]];
                        }
                        inWords[j] = inWords[j] + '';
                        break;
                    case 1:
                        tensComplication();
                        break;
                    case 2:
                        if (actnumber[i] == '0') {
                            inWords[j] = '';
                        } else if (actnumber[i - 1] !== '0' && actnumber[i - 2] !== '0') {
                            inWords[j] = iWords[actnumber[i]] + ' hundred';
                        } else {
                            inWords[j] = iWords[actnumber[i]] + ' hundred';
                        }
                        break;
                    case 3:
                        if (actnumber[i] == '0' || actnumber[i + 1] == '1') {
                            inWords[j] = '';
                        } else {
                            inWords[j] = iWords[actnumber[i]];
                        }
                        if (actnumber[i + 1] !== '0' || actnumber[i] > '0') {
                            inWords[j] = inWords[j] + ' thousand';
                        }
                        break;
                    case 4:
                        tensComplication();
                        break;
                    case 5:
                        if (actnumber[i] == '0' || actnumber[i + 1] == '1') {
                            inWords[j] = '';
                        } else {
                            inWords[j] = iWords[actnumber[i]];
                        }
                        if (actnumber[i + 1] !== '0' || actnumber[i] > '0') {
                            inWords[j] = inWords[j] + ' lakh';
                        }
                        break;
                    case 6:
                        tensComplication();
                        break;
                    case 7:
                        if (actnumber[i] == '0' || actnumber[i + 1] == '1') {
                            inWords[j] = '';
                        } else {
                            inWords[j] = iWords[actnumber[i]];
                        }
                        inWords[j] = inWords[j] + ' crore';
                        break;
                    case 8:
                        tensComplication();
                        break;
                    default:
                        break;
                }
                j++;
            }


            inWords.reverse();
            for (i = 0; i < inWords.length; i++) {
                finalWord += inWords[i];
            }
            return finalWord;
            }

        </script>

        <input type="text" name="bdt" id="bdt" />
        <input type="button" name="sr1" value="Click Here" onClick="convertAmount()"/>

        <div id="container"></div>

js fiddle

Here taka mean USD and paisa mean cent


I modified MC Shaman's code to fix the bug of single number having and appear before it

function numberToEnglish( n ) {
		
	var string = n.toString(), units, tens, scales, start, end, chunks, chunksLen, chunk, ints, i, word, words, and = 'and';

	/* Remove spaces and commas */
	string = string.replace(/[, ]/g,"");

	/* Is number zero? */
	if( parseInt( string ) === 0 ) {
		return 'zero';
	}
	
	/* Array of units as words */
	units = [ '', 'one', 'two', 'three', 'four', 'five', 'six', 'seven', 'eight', 'nine', 'ten', 'eleven', 'twelve', 'thirteen', 'fourteen', 'fifteen', 'sixteen', 'seventeen', 'eighteen', 'nineteen' ];
	
	/* Array of tens as words */
	tens = [ '', '', 'twenty', 'thirty', 'forty', 'fifty', 'sixty', 'seventy', 'eighty', 'ninety' ];
	
	/* Array of scales as words */
	scales = [ '', 'thousand', 'million', 'billion', 'trillion', 'quadrillion', 'quintillion', 'sextillion', 'septillion', 'octillion', 'nonillion', 'decillion', 'undecillion', 'duodecillion', 'tredecillion', 'quatttuor-decillion', 'quindecillion', 'sexdecillion', 'septen-decillion', 'octodecillion', 'novemdecillion', 'vigintillion', 'centillion' ];
	
	/* Split user arguemnt into 3 digit chunks from right to left */
	start = string.length;
	chunks = [];
	while( start > 0 ) {
		end = start;
		chunks.push( string.slice( ( start = Math.max( 0, start - 3 ) ), end ) );
	}
	
	/* Check if function has enough scale words to be able to stringify the user argument */
	chunksLen = chunks.length;
	if( chunksLen > scales.length ) {
		return '';
	}
	
	/* Stringify each integer in each chunk */
	words = [];
	for( i = 0; i < chunksLen; i++ ) {
		
		chunk = parseInt( chunks[i] );
		
		if( chunk ) {
			
			/* Split chunk into array of individual integers */
			ints = chunks[i].split( '' ).reverse().map( parseFloat );
		
			/* If tens integer is 1, i.e. 10, then add 10 to units integer */
			if( ints[1] === 1 ) {
				ints[0] += 10;
			}
			
			/* Add scale word if chunk is not zero and array item exists */
			if( ( word = scales[i] ) ) {
				words.push( word );
			}
			
			/* Add unit word if array item exists */
			if( ( word = units[ ints[0] ] ) ) {
				words.push( word );
			}
			
			/* Add tens word if array item exists */
			if( ( word = tens[ ints[1] ] ) ) {
				words.push( word );
			}
			
			/* Add 'and' string after units or tens integer if: */
			if( ints[0] || ints[1] ) {
				
				/* Chunk has a hundreds integer or chunk is the first of multiple chunks */
				if( ints[2] || (i + 1) > chunksLen ) {
					words.push( and );
				}

			
			}
			
			/* Add hundreds word if array item exists */
			if( ( word = units[ ints[2] ] ) ) {
				words.push( word + ' hundred' );
			}
			
		}
		
	}
	
	return words.reverse().join( ' ' );
	
}


// - - - - - Tests - - - - - -

function figure(val) {
  finalFig = numberToEnglish(val);
  document.getElementById("words").innerHTML = finalFig;
}
<span id="words"></span>
<input id="number" type="text" onkeyup=figure(this.value)  />


var inWords = function(totalRent){
//console.log(totalRent);
var a = ['','one ','two ','three ','four ', 'five ','six ','seven ','eight ','nine ','ten ','eleven ','twelve ','thirteen ','fourteen ','fifteen ','sixteen ','seventeen ','eighteen ','nineteen '];
var b = ['', '', 'twenty','thirty','forty','fifty', 'sixty','seventy','eighty','ninety'];
var number = parseFloat(totalRent).toFixed(2).split(".");
var num = parseInt(number[0]);
var digit = parseInt(number[1]);
//console.log(num);
if ((num.toString()).length > 9)  return 'overflow';
var n = ('000000000' + num).substr(-9).match(/^(\d{2})(\d{2})(\d{2})(\d{1})(\d{2})$/);
var d = ('00' + digit).substr(-2).match(/^(\d{2})$/);;
if (!n) return; var str = '';
str += (n[1] != 0) ? (a[Number(n[1])] || b[n[1][0]] + ' ' + a[n[1][1]]) + 'crore ' : '';
str += (n[2] != 0) ? (a[Number(n[2])] || b[n[2][0]] + ' ' + a[n[2][1]]) + 'lakh ' : '';
str += (n[3] != 0) ? (a[Number(n[3])] || b[n[3][0]] + ' ' + a[n[3][1]]) + 'thousand ' : '';
str += (n[4] != 0) ? (a[Number(n[4])] || b[n[4][0]] + ' ' + a[n[4][1]]) + 'hundred ' : '';
str += (n[5] != 0) ? (a[Number(n[5])] || b[n[5][0]] + ' ' + a[n[5][1]]) + 'Rupee ' : '';
str += (d[1] != 0) ? ((str != '' ) ? "and " : '') + (a[Number(d[1])] || b[d[1][0]] + ' ' + a[d[1][1]]) + 'Paise ' : 'Only!';
console.log(str);
return str;
}

This is modified code supports for Indian Rupee with 2 decimal place.


Another conversion that uses remainders and supports different languages:

function numberToWords(number) {
  var result = [];

  var fraction = number.toFixed(2).split('.');
  var integer_part = parseInt(fraction[0]);
  // var fractional_part = parseInt(fraction[1]); -- not handled here

  var previousNumber = null;
  for (var i = 0; i < fraction[0].length; i++) {
    var reminder = Math.floor(integer_part % 10);
    integer_part /= 10;
    var name = getNumberName(reminder, i, fraction[0].length, previousNumber);
    previousNumber = reminder;
    if (name)
      result.push(name);
  }

  result.reverse();
  return result.join(' ');
}

The getNumberName function is language-dependent and handles numbers up to 9999 (but it is easy to extend it to handle larger numbers):

function getNumberName(number, power, places, previousNumber) {
  var result = "";
  if (power == 1) {
    result = handleTeensAndTys(number, previousNumber);
  } else if (power == 0 && places != 1 || number == 0) {
    // skip number that was handled in teens and zero
  } else {
    result = locale.numberNames[number.toString()] + locale.powerNames[power.toString()];
  }

  return result;
}

handleTeensAndTys handles multiples of ten:

function handleTeensAndTys(number, previousNumber) {
  var result = "";
  if (number == 1) { // teens
    if (previousNumber in locale.specialTeenNames) {
      result = locale.specialTeenNames[previousNumber];    
    } else if (previousNumber in locale.specialTyNames) {
      result = locale.specialTyNames[previousNumber] + locale.teenSuffix;
    } else {
      result = locale.numberNames[previousNumber] + locale.teenSuffix;    
    }
  } else if (number == 0) { // previousNumber was not handled in teens
    result = locale.numberNames[previousNumber.toString()];
  } else { // other tys
    if (number in locale.specialTyNames) {
      result = locale.specialTyNames[number];
    } else {
      result = locale.numberNames[number];
    }
    result += locale.powerNames[1];
    if (previousNumber != 0) {
      result += " " + locale.numberNames[previousNumber.toString()];
    }
  }
  return result;
}

Finally, locale examples:

var locale = { // English
  numberNames: {1: "one", 2: "two", 3: "three", 4: "four", 5: "five", 6: "six", 7: "seven", 8: "eight", 9: "nine" },
  powerNames: {0: "", 1: "ty", 2: " hundred", 3: " thousand" },
  specialTeenNames: {0: "ten", 1: "eleven", 2: "twelve" },
  specialTyNames: {2: "twen", 3: "thir", 5: "fif" },
  teenSuffix: "teen"
};

var locale = { // Estonian
  numberNames: {1: "üks", 2: "kaks", 3: "kolm", 4: "neli", 5: "viis", 6: "kuus", 7: "seitse", 8: "kaheksa", 9: "üheksa"},
  powerNames: {0: "", 1: "kümmend", 2: "sada", 3: " tuhat" },
  specialTeenNames: {0: "kümme"},
  specialTyNames: {},
  teenSuffix: "teist"
};

Here's a JSFiddle with tests: https://jsfiddle.net/rcrxna7v/15/


Lot of good answers. I needed mine for Indian (South Asian) numbering system. I modified one of the codes above - attaching it here, in case, someone else needs this. In the Indian numbering system, groups after thousands are in in 2 digits, not 3 as in the western system.

var IS_SOUTH_ASIAN = true;
function int_to_words(int) {
  if (int === 0) return 'zero';

  var ONES_WORD  = ['','one','two','three','four','five','six','seven','eight','nine','ten','eleven','twelve','thirteen','fourteen','fifteen','sixteen','seventeen','eighteen','nineteen'];
  var TENS_WORD  = ['','','twenty','thirty','fourty','fifty','sixty','seventy','eighty','ninety'];
  var SCALE_WORD_WESTERN = ['','thousand','million','billion','trillion','quadrillion','quintillion','sextillion','septillion','octillion','nonillion'];
  var SCALE_WORD_SOUTH_ASIAN = ['','thousand','lakh','crore','arab','kharab','neel','padma','shankh','***','***'];

  var GROUP_SIZE = (typeof IS_SOUTH_ASIAN != "undefined" && IS_SOUTH_ASIAN) ? 2 : 3;
  var SCALE_WORD = (typeof IS_SOUTH_ASIAN != "undefined" && IS_SOUTH_ASIAN) ? SCALE_WORD_SOUTH_ASIAN : SCALE_WORD_WESTERN;


  // Return string of first three digits, padded with zeros if needed
  function get_first_3(str) {
    return ('000' + str).substr(-(3));
  }
  function get_first(str) { //-- Return string of first GROUP_SIZE digits, padded with zeros if needed, if group size is 2, make it size 3 by prefixing with a '0'
    return (GROUP_SIZE == 2 ? '0' : '') + ('000' + str).substr(-(GROUP_SIZE));
  }


  // Return string of digits with first three digits chopped off
  function get_rest_3(str) {
    return str.substr(0, str.length - 3);
  }
  function get_rest(str) { // Return string of digits with first GROUP_SIZE digits chopped off
    return str.substr(0, str.length - GROUP_SIZE);
  }

  // Return string of triplet convereted to words
  function triplet_to_words(_3rd, _2nd, _1st) {
    return  (_3rd == '0' ? '' : ONES_WORD[_3rd] + ' hundred ') + 
            (_1st == '0' ? TENS_WORD[_2nd] : TENS_WORD[_2nd] && TENS_WORD[_2nd] + '-' || '') + 
            (ONES_WORD[_2nd + _1st] || ONES_WORD[_1st]);  //-- 1st one returns one-nineteen - second one returns one-nine
  }

  // Add to result, triplet words with scale word
  function add_to_result(result, triplet_words, scale_word) {
    return triplet_words ? triplet_words + (scale_word && ' ' + scale_word || '') + ' ' + result : result;
  }

  function recurse (result, scaleIdx, first, rest) {
    if (first == '000' && rest.length === 0) return result;
    var newResult = add_to_result (result, triplet_to_words (first[0], first[1], first[2]), SCALE_WORD[scaleIdx]);
    return recurse (newResult, ++scaleIdx, get_first(rest), get_rest(rest));
  }

  return recurse ('', 0, get_first_3(String(int)), get_rest_3(String(int)));
}

while this system does use a for loop, It uses US english and is fast, accurate, and expandable(you can add infinite values to the "th" var and they will be included).

This function grabs the 3 groups of numbers backwards so it can get the number groups where a , would normally separate them in the numeric form. Then each group of three numbers is added to an array with the word form of just the 3 numbers(ex: one hundred twenty three). It then takes that new array list, and reverses it again, while adding the th var of the same index to the end of the string.

var ones = ['','one ','two ','three ','four ', 'five ','six ','seven ','eight ','nine ','ten ','eleven ','twelve ','thirteen ','fourteen ','fifteen ','sixteen ','seventeen ','eighteen ','nineteen '];
var tens = ['', '', 'twenty ','thirty ','forty ','fifty ', 'sixty ','seventy ','eighty ','ninety ', 'hundred '];
var th = ['', 'thousand ','million ','billion ', 'trillion '];

function numberToWord(number){
  var text = "";
  var size = number.length;

  var textList = [];
  var textListCount = 0;

  //get each 3 digit numbers
  for(var i = number.length-1; i >= 0; i -= 3){
    //get 3 digit group
    var num = 0;
    if(number[(i-2)]){num += number[(i-2)];}
    if(number[(i-1)]){num += number[(i-1)];}
    if(number[i]){num += number[i];}

    //remove any extra 0's from begining of number
    num = Math.floor(num).toString();

    if(num.length == 1 || num < 20){
      //if one digit or less than 20
      textList[textListCount] = ones[num];
    }else if(num.length == 2){
      //if 2 digits and greater than 20
      textList[textListCount] = tens[num[0]]+ones[num[1]];
    }else if(num.length == 3){
      //if 3 digits
      textList[textListCount] = ones[num[0]]+tens[10]+tens[num[1]]+ones[num[2]];
    }

    textListCount++;

  }

  //add the list of 3 digit groups to the string
  for(var i = textList.length-1; i >= 0; i--){
    if(textList[i] !== ''){text += textList[i]+th[i];} //skip if the number was 0
  }

  return text;
}

I modified @McShaman's code, converted it to CoffeeScript, and added docs via JSNice. Here's the result, for those interested (English):

###
    Convert an integer to an English string equivalent
    @param {Integer} number the integer to be converted
    @return {String} the English number equivalent
###
inWords = (number) ->
    ###
        @property {Array}
    ###
    englishIntegers = [
        ""
        "one "
        "two "
        "three "
        "four "
        "five "
        "six "
        "seven "
        "eight "
        "nine "
        "ten "
        "eleven "
        "twelve "
        "thirteen "
        "fourteen "
        "fifteen "
        "sixteen "
        "seventeen "
        "eighteen "
        "nineteen "
    ]

    ###
        @property {Array}
    ###
    englishIntegerTens = [
        ""
        ""
        "twenty"
        "thirty"
        "forty"
        "fifty"
        "sixty"
        "seventy"
        "eighty"
        "ninety"
    ]

    ###
        @property {Array}
    ###
    englishIntegerThousands = [
        "thousand"
        "million"
        ""
    ]
    number = number.toString()
    return "" if number.length > 9

    ###
        @property {string}
    ###
    number = ("000000000" + number).substr(-9)

    ###
      @property {(Array.<string>|null)}
      ###
    number = number.match(/.{3}/g)

    ###
        @property {string}
    ###
    convertedWords = ""

    ###
        @property {number}
    ###
    i = 0
    while i < englishIntegerThousands.length

        ###
            @property {string}
        ###
        currentNumber = number[i]

        ###
            @property {string}
        ###
        tempResult = ""
        tempResult += (if convertedWords isnt "" then " " + englishIntegerThousands[i] + " " else "")
        tempResult += (if currentNumber[0] isnt 0 then englishIntegers[Number(currentNumber[0])] + "hundred " else "")

        ###
            @property {string}
        ###
        currentNumber = currentNumber.substr(1)
        tempResult += (if currentNumber isnt 0 then ((if tempResult isnt "" then "and " else "")) + (englishIntegers[Number(currentNumber)] or englishIntegerTens[currentNumber[0]] + " " + englishIntegers[currentNumber[1]]) else "")
        convertedWords += tempResult
        i++
    convertedWords

Though, this question has been answered - still I want to share something I recently developed in java script (based on the logic of an old C#. Net implementation I found in Internet) for converting Indian currency values to Words. It can handle up to 40 digits. You can have a look.

Usage: InrToWordConverter.Initialize();. var inWords = InrToWordConverter.ConvertToWord(amount);

Implementation:

htPunctuation = {};
listStaticSuffix = {};
listStaticPrefix = {};
listHelpNotation = {};

var InrToWordConverter = function () {

};

InrToWordConverter.Initialize = function () {
    InrToWordConverter.LoadStaticPrefix();
    InrToWordConverter.LoadStaticSuffix();
    InrToWordConverter.LoadHelpofNotation();
};

InrToWordConverter.ConvertToWord = function (value) {
    value = value.toString();

    if (value) {
        var tokens = value.split(".");
        var rsPart = "";
        var psPart = "";
        if (tokens.length === 2) {
            rsPart = String.trim(tokens[0]) || "0";
            psPart = String.trim(tokens[1]) || "0";
        }
        else if (tokens.length === 1) {
            rsPart = String.trim(tokens[0]) || "0";
            psPart = "0";
        }
        else {
            rsPart = "0";
            psPart = "0";
        }

        htPunctuation = {};
        var rsInWords = InrToWordConverter.ConvertToWordInternal(rsPart) || "Zero";
        var psInWords = InrToWordConverter.ConvertToWordInternal(psPart) || "Zero";

        var result = "Rupees " + rsInWords + "and " + psInWords + " Paise.";
        return result;
    }
};

InrToWordConverter.ConvertToWordInternal = function (value) {
    var convertedString = "";
    if (!(value.toString().length > 40))
    {
        if (InrToWordConverter.IsNumeric(value.toString()))
        {
            try
            {
                var strValue = InrToWordConverter.Reverse(value);
                switch (strValue.length)
                {
                    case 1:
                        if (parseInt(strValue.toString()) > 0) {
                            convertedString = InrToWordConverter.GetWordConversion(value);
                        }
                        else {
                            convertedString = "Zero ";
                        }
                        break;
                    case 2:
                        convertedString = InrToWordConverter.GetWordConversion(value);
                        break;
                    default:
                        InrToWordConverter.InsertToPunctuationTable(strValue);
                        InrToWordConverter.ReverseHashTable();
                        convertedString = InrToWordConverter.ReturnHashtableValue();
                        break;
                }
            }
            catch (exception) {
                convertedString = "Unexpected Error Occured <br/>";
            }
        }
        else {
            convertedString = "Please Enter Numbers Only, Decimal Values Are not supported";
        }
    }
    else {
        convertedString = "Please Enter Value in Less Then or Equal to 40 Digit";
    }
    return convertedString;
};

InrToWordConverter.IsNumeric = function (valueInNumeric) {
    var isFine = true;
    valueInNumeric = valueInNumeric || "";
    var len = valueInNumeric.length;
    for (var i = 0; i < len; i++) {
        var ch = valueInNumeric[i];
        if (!(ch >= '0' && ch <= '9')) {
            isFine = false;
            break;
        }
    }
    return isFine;
};

InrToWordConverter.ReturnHashtableValue = function () {
    var strFinalString = "";
    var keysArr = [];
    for (var key in htPunctuation) {
        keysArr.push(key);
    }
    for (var i = keysArr.length - 1; i >= 0; i--) {
        var hKey = keysArr[i];
        if (InrToWordConverter.GetWordConversion((htPunctuation[hKey]).toString()) !== "") {
            strFinalString = strFinalString + InrToWordConverter.GetWordConversion((htPunctuation[hKey]).toString()) + InrToWordConverter.StaticPrefixFind((hKey).toString());
        }
    }
    return strFinalString;
};

InrToWordConverter.ReverseHashTable = function () {
    var htTemp = {};
    for (var key in htPunctuation) {
        var item = htPunctuation[key];
        htTemp[key] = InrToWordConverter.Reverse(item.toString());
    }
    htPunctuation = {};
    htPunctuation = htTemp;
};

InrToWordConverter.InsertToPunctuationTable = function (strValue) {
    htPunctuation[1] = strValue.substr(0, 3).toString();
    var j = 2;
    for (var i = 3; i < strValue.length; i = i + 2) {
        if (strValue.substr(i).length > 0) {
            if (strValue.substr(i).length >= 2) {
                htPunctuation[j] = strValue.substr(i, 2).toString();
            }
            else {
                htPunctuation[j] = strValue.substr(i, 1).toString();
            }
        }
        else {
            break;
        }
        j++;

    }
};

InrToWordConverter.Reverse = function (strValue) {
    var reversed = "";
    for (var i in strValue) {
        var ch = strValue[i];
        reversed = ch + reversed;
    }
    return reversed;
};

InrToWordConverter.GetWordConversion = function (inputNumber) {
    var toReturnWord = "";
    if (inputNumber.length <= 3 && inputNumber.length > 0) {
        if (inputNumber.length === 3) {
            if (parseInt(inputNumber.substr(0, 1)) > 0) {
                toReturnWord = toReturnWord + InrToWordConverter.StaticSuffixFind(inputNumber.substr(0, 1)) + "Hundred ";
            }

            var tempString = InrToWordConverter.StaticSuffixFind(inputNumber.substr(1, 2));

            if (tempString === "")
            {
                toReturnWord = toReturnWord + InrToWordConverter.StaticSuffixFind(inputNumber.substr(1, 1) + "0");
                toReturnWord = toReturnWord + InrToWordConverter.StaticSuffixFind(inputNumber.substr(2, 1));
            }
            toReturnWord = toReturnWord + tempString;
        }
        if (inputNumber.length === 2)
        {
            var tempString = InrToWordConverter.StaticSuffixFind(inputNumber.substr(0, 2));
            if (tempString === "")
            {
                toReturnWord = toReturnWord + InrToWordConverter.StaticSuffixFind(inputNumber.substr(0, 1) + "0");
                toReturnWord = toReturnWord + InrToWordConverter.StaticSuffixFind(inputNumber.substr(1, 1));
            }
            toReturnWord = toReturnWord + tempString;
        }
        if (inputNumber.length === 1)
        {
            toReturnWord = toReturnWord + InrToWordConverter.StaticSuffixFind(inputNumber.substr(0, 1));
        }

    }
    return toReturnWord;
};

InrToWordConverter.StaticSuffixFind = function (numberKey) {
    var valueFromNumber = "";
    for (var key in listStaticSuffix) {
        if (String.trim(key.toString()) === String.trim(numberKey)) {
            valueFromNumber = listStaticSuffix[key].toString();
            break;
        }
    }
    return valueFromNumber;
};

InrToWordConverter.StaticPrefixFind = function (numberKey) {
    var valueFromNumber = "";
    for (var key in listStaticPrefix) {
        if (String.trim(key) === String.trim(numberKey)) {
            valueFromNumber = listStaticPrefix[key].toString();
            break;
        }
    }
    return valueFromNumber;
};

InrToWordConverter.StaticHelpNotationFind = function (numberKey) {
    var helpText = "";
    for (var key in listHelpNotation) {
        if (String.trim(key.toString()) === String.trim(numberKey)) {
            helpText = listHelpNotation[key].toString();
            break;
        }
    }
    return helpText;
};

InrToWordConverter.LoadStaticPrefix = function () {
    listStaticPrefix[2] = "Thousand ";
    listStaticPrefix[3] = "Lac ";
    listStaticPrefix[4] = "Crore ";
    listStaticPrefix[5] = "Arab ";
    listStaticPrefix[6] = "Kharab ";
    listStaticPrefix[7] = "Neel ";
    listStaticPrefix[8] = "Padma ";
    listStaticPrefix[9] = "Shankh ";
    listStaticPrefix[10] = "Maha-shankh ";
    listStaticPrefix[11] = "Ank ";
    listStaticPrefix[12] = "Jald ";
    listStaticPrefix[13] = "Madh ";
    listStaticPrefix[14] = "Paraardha ";
    listStaticPrefix[15] = "Ant ";
    listStaticPrefix[16] = "Maha-ant ";
    listStaticPrefix[17] = "Shisht ";
    listStaticPrefix[18] = "Singhar ";
    listStaticPrefix[19] = "Maha-singhar ";
    listStaticPrefix[20] = "Adant-singhar ";
};

InrToWordConverter.LoadStaticSuffix = function () {
    listStaticSuffix[1] = "One ";
    listStaticSuffix[2] = "Two ";
    listStaticSuffix[3] = "Three ";
    listStaticSuffix[4] = "Four ";
    listStaticSuffix[5] = "Five ";
    listStaticSuffix[6] = "Six ";
    listStaticSuffix[7] = "Seven ";
    listStaticSuffix[8] = "Eight ";
    listStaticSuffix[9] = "Nine ";
    listStaticSuffix[10] = "Ten ";
    listStaticSuffix[11] = "Eleven ";
    listStaticSuffix[12] = "Twelve ";
    listStaticSuffix[13] = "Thirteen ";
    listStaticSuffix[14] = "Fourteen ";
    listStaticSuffix[15] = "Fifteen ";
    listStaticSuffix[16] = "Sixteen ";
    listStaticSuffix[17] = "Seventeen ";
    listStaticSuffix[18] = "Eighteen ";
    listStaticSuffix[19] = "Nineteen ";
    listStaticSuffix[20] = "Twenty ";
    listStaticSuffix[30] = "Thirty ";
    listStaticSuffix[40] = "Fourty ";
    listStaticSuffix[50] = "Fifty ";
    listStaticSuffix[60] = "Sixty ";
    listStaticSuffix[70] = "Seventy ";
    listStaticSuffix[80] = "Eighty ";
    listStaticSuffix[90] = "Ninty ";
};

InrToWordConverter.LoadHelpofNotation = function () {
    listHelpNotation[2] = "=1,000 (3 Trailing Zeros)";
    listHelpNotation[3] = "=1,00,000 (5 Trailing Zeros)";
    listHelpNotation[4] = "=1,00,00,000 (7 Trailing Zeros)";
    listHelpNotation[5] = "=1,00,00,00,000 (9 Trailing Zeros)";
    listHelpNotation[6] = "=1,00,00,00,00,000 (11 Trailing Zeros)";
    listHelpNotation[7] = "=1,00,00,00,00,00,000 (13 Trailing Zeros)";
    listHelpNotation[8] = "=1,00,00,00,00,00,00,000 (15 Trailing Zeros)";
    listHelpNotation[9] = "=1,00,00,00,00,00,00,00,000 (17 Trailing Zeros)";
    listHelpNotation[10] = "=1,00,00,00,00,00,00,00,00,000 (19 Trailing Zeros)";
    listHelpNotation[11] = "=1,00,00,00,00,00,00,00,00,00,000 (21 Trailing Zeros)";
    listHelpNotation[12] = "=1,00,00,00,00,00,00,00,00,00,00,000 (23 Trailing Zeros)";
    listHelpNotation[13] = "=1,00,00,00,00,00,00,00,00,00,00,00,000 (25 Trailing Zeros)";
    listHelpNotation[14] = "=1,00,00,00,00,00,00,00,00,00,00,00,00,000 (27 Trailing Zeros)";
    listHelpNotation[15] = "=1,00,00,00,00,00,00,00,00,00,00,00,00,00,000 (29 Trailing Zeros)";
    listHelpNotation[16] = "=1,00,00,00,00,00,00,00,00,00,00,00,00,00,00,000 (31 Trailing Zeros)";
    listHelpNotation[17] = "=1,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,000 (33 Trailing Zeros)";
    listHelpNotation[18] = "=1,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,000 (35 Trailing Zeros)";
    listHelpNotation[19] = "=1,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,000 (37 Trailing Zeros)";
    listHelpNotation[20] = "=1,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,00,000 (39 Trailing Zeros)";
};
    if (!String.trim) {
    String.trim = function (str) {
        var result = "";
        var firstNonWhiteSpaceFound = false;
        var startIndex = -1;
        var endIndex = -1;
        if (str) {
            for (var i = 0; i < str.length; i++) {
                if (firstNonWhiteSpaceFound === false) {
                    if (str[i] === ' ' || str[i] === '\t') {
                        continue;
                    }
                    else {
                        firstNonWhiteSpaceFound = true;
                        startIndex = i;
                        endIndex = i;
                    }
                }
                else {
                    if (str[i] === ' ' || str[i] === '\t') {
                        continue;
                    }
                    else {
                        endIndex = i;
                    }
                }
            }
            if (startIndex !== -1 && endIndex !== -1) {
                result = str.slice(startIndex, endIndex + 1);
            }
        }
        return result;
    };
}

Below are the translations from

  • integer to word
  • float to word
  • money to word

Test cases are at the bottom

var ONE_THOUSAND = Math.pow(10, 3);
var ONE_MILLION = Math.pow(10, 6);
var ONE_BILLION = Math.pow(10, 9);
var ONE_TRILLION = Math.pow(10, 12);
var ONE_QUADRILLION = Math.pow(10, 15);
var ONE_QUINTILLION = Math.pow(10, 18);

function integerToWord(integer) {
  var prefix = '';
  var suffix = '';

  if (!integer){ return "zero"; }
  
  if(integer < 0){
    prefix = "negative";
    suffix = integerToWord(-1 * integer);
    return prefix + " " + suffix;
  }
  if(integer <= 90){
    switch (integer) {
      case integer < 0:
        prefix = "negative";
        suffix = integerToWord(-1 * integer);
        return prefix + " "  + suffix;
      case 1: return "one";
      case 2: return "two";
      case 3: return "three";
      case 4:  return "four";
      case 5: return "five";
      case 6: return "six";
      case 7: return "seven";
      case 8: return "eight";
      case 9: return "nine";
      case 10: return "ten";
      case 11: return "eleven";
      case 12: return "twelve";
      case 13: return "thirteen";
      case 14: return "fourteen";
      case 15: return "fifteen";
      case 16: return "sixteen";
      case 17: return "seventeen";
      case 18: return "eighteen";
      case 19: return "nineteen";
      case 20: return "twenty";
      case 30: return "thirty";
      case 40: return "forty";
      case 50: return "fifty";
      case 60: return "sixty";
      case 70: return "seventy";
      case 80: return "eighty";
      case 90: return "ninety";
      default: break;
    }
  }

  if(integer < 100){
    prefix = integerToWord(integer - integer % 10);
    suffix = integerToWord(integer % 10);
    return prefix + "-"  + suffix;
  }

  if(integer < ONE_THOUSAND){
    prefix = integerToWord(parseInt(Math.floor(integer / 100), 10) )  + " hundred";
    if (integer % 100){ suffix = " and "  + integerToWord(integer % 100); }
    return prefix + suffix;
  }

  if(integer < ONE_MILLION){
    prefix = integerToWord(parseInt(Math.floor(integer / ONE_THOUSAND), 10))  + " thousand";
    if (integer % ONE_THOUSAND){ suffix = integerToWord(integer % ONE_THOUSAND); }
  }
  else if(integer < ONE_BILLION){
    prefix = integerToWord(parseInt(Math.floor(integer / ONE_MILLION), 10))  + " million";
    if (integer % ONE_MILLION){ suffix = integerToWord(integer % ONE_MILLION); }
  }
  else if(integer < ONE_TRILLION){
    prefix = integerToWord(parseInt(Math.floor(integer / ONE_BILLION), 10))  + " billion";
    if (integer % ONE_BILLION){ suffix = integerToWord(integer % ONE_BILLION); }
  }
  else if(integer < ONE_QUADRILLION){
    prefix = integerToWord(parseInt(Math.floor(integer / ONE_TRILLION), 10))  + " trillion";
    if (integer % ONE_TRILLION){ suffix = integerToWord(integer % ONE_TRILLION); }
  }
  else if(integer < ONE_QUINTILLION){
    prefix = integerToWord(parseInt(Math.floor(integer / ONE_QUADRILLION), 10))  + " quadrillion";
    if (integer % ONE_QUADRILLION){ suffix = integerToWord(integer % ONE_QUADRILLION); }
  } else {
    return '';
  }
  return prefix + " "  + suffix;
}

function moneyToWord(value){
  var decimalValue = (value % 1);
  var integer = value - decimalValue;
  decimalValue = Math.round(decimalValue * 100);
  var decimalText = !decimalValue? '': integerToWord(decimalValue) + ' cent' + (decimalValue === 1? '': 's');
  var integerText= !integer? '': integerToWord(integer) + ' dollar' + (integer === 1? '': 's');
  return (
    integer && !decimalValue? integerText:
    integer && decimalValue? integerText + ' and ' + decimalText:
    !integer && decimalValue? decimalText:
    'zero cents'
  );
}

function floatToWord(value){
  var decimalValue = (value % 1);
  var integer = value - decimalValue;
  decimalValue = Math.round(decimalValue * 100);
  var decimalText = !decimalValue? '':
    decimalValue < 10? "point o' " + integerToWord(decimalValue):
    decimalValue % 10 === 0? 'point ' + integerToWord(decimalValue / 10):
    'point ' + integerToWord(decimalValue);
  return (
    integer && !decimalValue? integerToWord(integer):
    integer && decimalValue? [integerToWord(integer),  decimalText].join(' '):
    !integer && decimalValue? decimalText:
    integerToWord(0)
  );
}

// test
(function(){
  console.log('integerToWord ==================================');
  for(var i = 0; i < 101; ++i){
    console.log('%s=%s', i, integerToWord(i));
  }
  console.log('floatToWord ====================================');
  i = 131;
  while(i--){
    console.log('%s=%s', i / 100, floatToWord(i / 100));
  }
  console.log('moneyToWord ====================================');
  for(i = 0; i < 131; ++i){
    console.log('%s=%s', i / 100, moneyToWord(i / 100));
  }
}());


You can check my version from github. It is not so hard way. I test this for the numbers between 0 and 9999, but you can extend array if you would like digits to words


This is also in response to naomik's excellent post! Unfortunately I don't have the rep to post in the correct place but I leave this here in case it can help anyone.

If you need British English written form you need to make some adaptions to the code. British English differs from the American in a couple of ways. Basically you need to insert the word 'and' in two specific places.

  1. After a hundred assuming there are tens and ones. E.g One hundred and ten. One thousand and seventeen. NOT One thousand one hundred and.
  2. In certain edges, after a thousand, a million, a billion etc. when there are no smaller units. E.g. One thousand and ten. One million and forty four. NOT One million and one thousand.

The first situation can be addressed by checking for 10s and 1s in the makeGroup method and appending 'and' when they exist.

makeGroup = ([ones,tens,huns]) => {
var adjective = this.num(ones) ? ' hundred and ' : this.num(tens) ? ' hundred and ' : ' hundred';
return [
  this.num(huns) === 0 ? '' : this.a[huns] + adjective,
  this.num(ones) === 0 ? this.b[tens] : this.b[tens] && this.b[tens] + '-' || '',
  this.a[tens+ones] || this.a[ones]
].join('');

};

The second case is more complicated. It is equivalent to

  • add 'and' to 'a million, a thousand', or 'a billion' if the antepenultimate number is zero. e.g.

1,100,057 one million one hundred thousand and fifty seven. 5,000,006 five million and six

I think this could be implemented in @naomik's code through the use of a filter function but I wasn't able to work out how. In the end I settled on hackily looping through the returned array of words and using indexOf to look for instances where the word 'hundred' was missing from the final element.


I've just written paisa.js to do this, and it handles lakhs and crores correctly as well, can check it out. The core looks a bit like this:

const regulars = [
  {
    1: 'one', 2: 'two', 3: 'three', 4: 'four', 5: 'five', 6: 'six', 7: 'seven', 8: 'eight', 9: 'nine'
  },
  {
    2: 'twenty', 3: 'thirty', 4: 'forty', 5: 'fifty', 6: 'sixty', 7: 'seventy', 8: 'eighty', 9: 'ninety'
  }
]

const exceptions = {
  10: 'ten',
  11: 'eleven',
  12: 'twelve',
  13: 'thirteen',
  14: 'fourteen',
  15: 'fifteen',
  16: 'sixteen',
  17: 'seventeen',
  18: 'eighteen',
  19: 'nineteen'
}

const partInWords = (part) => {
  if (parseInt(part) === 0) return
  const digits = part.split('')
  const words = []
  if (digits.length === 3) {
    words.push([regulars[0][digits.shift()], 'hundred'].join(' '))
  }
  if (exceptions[digits.join('')]) {
    words.push(exceptions[digits.join('')])
  } else {
    words.push(digits.reverse().reduce((memo, el, i) => {
      memo.unshift(regulars[i][el])
      return memo
    }, []).filter(w => w).join(' '))
  }
  return words.filter(w => w.trim().length).join(' and ')
}

Convert digits to word in French language using JavaScript and html - original French words

    <html>
        <head>
            <title>Number to word</title>

            <script>
                function toWords() {
                    var s = document.getElementById('value').value;
                    var th = ['','mille','million', 'milliard','billion'];
                    var dg = ['zéro','un','deux','trois','quatre', 'cinq','six','sept','huit','neuf'];
                    var tn = 

['dix','onze','douze','treize', 'quatorze','quinze','seize', 'dix-sept','dix-huit','dix-neuf'];
                var tw = ['vingt','trente','quarante','cinquante', 'soixante','soixante-dix','quatre-vingt','quatre-vingt-dix'];
                s = s.toString();
                s = s.replace(/[\, ]/g,'');
                if (s != parseFloat(s)) return 'not a number';
                var x = s.indexOf('.');
                if (x == -1)
                    x = s.length;
                if (x > 15)
                    return 'too big';
                var n = s.split(''); 
                var str = '';
                var sk = 0;
                for (var i=0;   i < x;  i++) {
                    if ((x-i)%3==2) { 
                        if (n[i] == '1') {

                            str += tn[Number(n[i+1])] + ' ';
                            i++;
                            sk=1;
                        } else if (n[i]!=0) { 
                            if(s!=21 && s!=31 && s!=41 && s!=51 && s!=61 && s!=71 && s!=72 && s!=73 && s!=74 && s!=75 && s!=76 && s!=100 && s!=91 && s!=92 && s!=93 && s!=94 && s!=95 && s!=96){
                            if(s==20 || s==30 || s==40 || s==50 || s==60 || s==70 || s==80 || s==90){
                            str += tw[n[i]-2] + ' ';} // for not to display hyphens for 20,30...90 
                            else{
                            str += tw[n[i]-2] + '-';}
                            sk=1;
                            }
                        }
                    } else if (n[i]!=0) {
                        if(s!=21 && s!=31 && s!=41 && s!=51 && s!=61 && s!=71 && s!=72 && s!=73 && s!=74 && s!=75 && s!=76 && s!=100 && s!=91 && s!=92 && s!=93 && s!=94 && s!=95 && s!=96){

                        str += dg[n[i]] +' ';
                        if ((x-i)%3==0) str += 'hundert ';  // for start from 101 - 

                        sk=1;
                        }
                    }
                    if ((x-i)%3==1) {
                        if(s!=21 && s!=31 && s!=41 && s!=51 && s!=61 && s!=71 && s!=72 && s!=73 && s!=74 && s!=75 && s!=76 && s!=100 && s!=91 && s!=92 && s!=93 && s!=94 && s!=95 && s!=96){
                        if (sk)
                            str += th[(x-i-1)/3] + ' ';
                        sk=0;
                        }
                    }
                }

                if (x != s.length) {
                    var y = s.length;
                    //str += 'point ';
                    //for (var i=x+1; i<y; i++)
                    //  str += dg[n[i]] +' ';
                    str += 'virgule ';
                     var counter=0;
                     for (var i=x+1; i<y; i++){
                        if ((y-i)%3==2) { 
                                            if (n[i] == '1') {
                                                            str += tn[Number(n[i+1])] + ' ';
                                                            i++;
                                                            counter=1;
                                            } else if (n[i]!=0) {
                                                            str += tw[n[i]-2] + '-';
                                                            counter=1;
                                            }
                                        }else if (n[i]!=0) { // 0235
                                            str += dg[n[i]] +' ';
                                        }
                     }

                }

                if (s!=21 && s!=31 && s!=41 && s!=51 && s!=61 && s!=71 && s!=72 && s!=73 && s!=74 && s!=75 && s!=76 && s!=100 && s!=91 && s!=92 && s!=93 && s!=94 && s!=95 && s!=96){
                document.getElementById("demo").innerHTML = str.replace(/\s+/g,' ')

                }
                else if (s==21){
                str = 'vingt-et-un'
                document.getElementById("demo").innerHTML = str;
                }//alert(str.replace(/\s+/g,' '));
                else if (s==31){
                str = 'trente-et-un'
                document.getElementById("demo").innerHTML = str;}
                else if (s==41){
                str = 'quarante-et-un'
                document.getElementById("demo").innerHTML = str;}
                else if (s==51){
                str = 'cinquante-et-un'
                document.getElementById("demo").innerHTML = str;}
                else if (s==61){
                str = 'soixante-et-un'
                document.getElementById("demo").innerHTML = str;}
                else if (s==71){
                str = 'soixante-et-onze'
                document.getElementById("demo").innerHTML = str;}
                else if (s==72){
                str = 'soixante-douze'
                document.getElementById("demo").innerHTML = str;}
                else if (s==73){
                str = 'soixante-treize'
                document.getElementById("demo").innerHTML = str;}
                else if (s==74){
                str = 'soixante-quatorze'
                document.getElementById("demo").innerHTML = str;}
                else if (s==75){
                str = 'soixante-quinze'
                document.getElementById("demo").innerHTML = str;}
                else if (s==76){
                str = 'soixante-seize'
                document.getElementById("demo").innerHTML = str;}
                else if (s==100){
                str = 'cent'
                document.getElementById("demo").innerHTML = str;}
                else if (s==91){
                str = 'quatre-vingt-onze'
                document.getElementById("demo").innerHTML = str;}
                else if (s==92){
                str = 'quatre-vingt-douze'
                document.getElementById("demo").innerHTML = str;}
                else if (s==93){
                str = 'quatre-vingt-treize'
                document.getElementById("demo").innerHTML = str;}
                else if (s==94){
                str = 'quatre-vingt-quatorze'
                document.getElementById("demo").innerHTML = str;}   
                else if (s==95){
                str = 'quatre-vingt-quinze'
                document.getElementById("demo").innerHTML = str;}   
                else if (s==96){
                str = 'quatre-vingt-seize'
                document.getElementById("demo").innerHTML = str;}               
            }
        </script>
    </head>
    <body>
        <p>Enter only numbers (max 15 digits) : </p>
        <input type="text" name="value" id='value' /><br>
        <input type="button" value="submit" onclick="toWords()" />
        <p id="demo"></p>
        <p id="demo1"></p>
    </body>
</html> 

I have created customized function ntsConvert() to convert number to words

function ntsConvert(value) {
let input = String(value).split('');
let mapData = {
	"0": "Zero",
	"1": "One",
	"2": "Two",
	"3": "Three",
	"4": "Four",
	"5": "Five",
	"6": "Six",
	"7": "Seven",
	"8": "Eight",
	"9": "Nine"
};
let output = '';
var tempArray = []
for (let i = 0; i < input.length; i++) {
	tempArray.push(mapData[input[i]])
}
output = tempArray.join(' ');
return output;
}

console.log(ntsConvert(12345)) // 'One Two Three Four Five'


Try this code with a Turkish currency compliant JavaScript

function dene() {
         var inpt = document.getElementById("tar1").value;
         var spt = inpt.split('');
         spt.reverse();

         var tek = ["", "Bir", "?ki", "Üç", "Dört", "Be?", "Alt?", "Yedi", "Sekiz", "Dokuz"];
         var onlu = ["", "On", "Yirmi", "Otuz", "K?rk", "Elli", "Atm??", "Yetmi?", "Seksen", "Doksan"];
         var Yuz = ["", "Yüz", "?kiYüz", "Üçyüz", "DörtYüz", "Be?Yüz", "Alt?Yüz", "YediYüz", "SekizYüz", "DokuzYüz"];
         var ska = ["", "", "", "", "Bin", "Milyon", "Milyar", "Trilyon", "Katrilyon", "Kentilyon"];
         var i, j;
         var bas3 = "";
         var bas6 = "";
         var bas9 = "";
         var bas12 = "";
         var total;

               for(i = 0; i < 1; i++) {

                      bas3 += Yuz[spt[i+2]] + onlu[spt[i+1]] + tek[spt[i]];
                      bas6 += Yuz[spt[i+5]] + onlu[spt[i+4]] + tek[spt[i+3]] + ska[4];
                      bas9 += Yuz[spt[i+8]] + onlu[spt[i+7]] + tek[spt[i+6]] + ska[5];
                      bas12 += Yuz[spt[i+11]] + onlu[spt[i+10]] + tek[spt[i+9]] + ska[6];


                   if(inpt.length < 4) {
                       bas6 = '';
                       bas9 = '';
                   }
                   if(inpt.length > 6 && inpt.slice(5, 6) == 0) {
                     bas6 = bas6.replace(/Bin/g, '');
                   }
                   if(inpt.length < 7) {
                       bas9 = '';
                   } 
                   if(inpt.length > 9 && inpt.slice(1,3) == 000){
                       bas9 = bas9.replace(/Milyon/g, '');
                   }

                   if(inpt.length < 10) {
                    bas12 = '';
                 }
             }

         total = bas12 + bas9 + bas6 + bas3;
         total = total.replace(NaN, '');
         total = total.replace(undefined, '');

        document.getElementById('demo').innerHTML = 
            total;


     }

 var units = ["", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine"];
var tens = ["", "", "twenty", "thirty", "forty", "fifty", "sixty", "seventy", "eighty", "ninety"];



function convert7digitIntoWords(num) {
    var remainder = num % 1000000
    var hun = num - remainder;
    var div = Math.floor(num / 100000);
    if (remainder !== 0)
        return (convert2digitIntoWords(div) + " lakhs " + convert5digitIntoWords(remainder % 100000))
    else
        return (convert2digitIntoWords(div) + " lakhs ")
}

function convert6digitIntoWords(num) {
    var remainder = num % 100000
    var hun = num - remainder;
    var div = Math.floor(num / 100000);
    if (remainder !== 0)
        return (units[div] + " lakh " + convert5digitIntoWords(remainder))
    else
        return (units[div] + " lakh ")
}

function convert5digitIntoWords(num) {
    var remainder = num % 10000
    var hun = num - remainder;
    var div = Math.floor(num / 1000);
    if (remainder !== 0)
        return (convert2digitIntoWords(div) + " thousand " + convert3digitIntoWords(remainder % 1000))
    else
        return (convert2digitIntoWords(div) + " thousand")
}

function convert4digitIntoWords(num) {
    var remainder = num % 1000
    var hun = num - remainder;
    var div = Math.floor(num / 1000);
    if (remainder !== 0)
        return (units[div] + " thousand " + convert3digitIntoWords(remainder))
    else
        return (units[div] + " thousand")
}


function convert3digitIntoWords(num) {
    var remainder = num % 100
    var hun = num - remainder;
    var div = Math.floor(num / 100);
    if (remainder !== 0)
        return (units[div] + " hundred " + convert2digitIntoWords(remainder))
    else
        return (units[div] + " hundred ")
}

function convert2digitIntoWords(num) {
    var remainder = num % 10;
    var div = Math.floor(num / 10);
    return (tens[div] + " " + convertNumIntoWords(remainder));
}

function convertNumIntoWords(num) {

    switch (("" + num).length) {
        case 1:
            return units[num];
        case 2:
            return convert2digitIntoWords(num);
        case 3:
            return convert3digitIntoWords(num)
        case 4:
            return convert4digitIntoWords(num)
        case 5:
            return convert5digitIntoWords(num)
        case 6:
            return convert6digitIntoWords(num)
        case 7:
            return convert7digitIntoWords(num)
        default:
            return "cannot be converted"
    }
}

console.log(convertNumIntoWords(3445125));

My solution is based on Juan Gaitán's solution for Indian currency, works up to crores.

function valueInWords(value) {
    let ones = ['', 'one', 'two', 'three', 'four',
            'five', 'six', 'seven', 'eight', 'nine',
            'ten', 'eleven', 'twelve', 'thirteen', 'fourteen',
            'fifteen', 'sixteen', 'seventeen', 'eighteen', 'nineteen'];   
    let tens = ['twenty','thirty', 'forty','fifty', 'sixty', 'seventy', 'eighty', 'ninety'];
    let digit = 0;   
    if (value < 20) return ones[value];   
    if (value < 100) {     
        digit = value % 10; //remainder     
        return tens[Math.floor(value/10)-2] + " " + (digit > 0 ? ones[digit] : "");   
    }
    if (value < 1000) {    
         return ones[Math.floor(value/100)] + " hundred " + (value % 100 > 0 ? valueInWords(value % 100) : "");   
    }   
    if (value < 100000) {     
        return valueInWords(Math.floor(value/1000)) + " thousand " + (value % 1000 > 0 ? valueInWords(value % 1000) : "");   
    }   
    if (value < 10000000) {     
        return valueInWords(Math.floor(value/100000)) + " lakh " + (value % 100000 > 0 ? valueInWords(value % 100000) : "");   
    }   
    return valueInWords(Math.floor(value/10000000)) + " crore " + (value % 10000000 > 0 ? valueInWords(value % 10000000) : ""); 
}

    function numberToEnglish( n ) {
        
        var string = n.toString(), units, tens, scales, start, end, chunks, chunksLen, chunk, ints, i, word, words, and = 'and';

        /* Remove spaces and commas */
        string = string.replace(/[, ]/g,"");

        /* Is number zero? */
        if( parseInt( string ) === 0 ) {
            return 'zero';
        }
        
        /* Array of units as words */
        units = [ '', 'one', 'two', 'three', 'four', 'five', 'six', 'seven', 'eight', 'nine', 'ten', 'eleven', 'twelve', 'thirteen', 'fourteen', 'fifteen', 'sixteen', 'seventeen', 'eighteen', 'nineteen' ];
        
        /* Array of tens as words */
        tens = [ '', '', 'twenty', 'thirty', 'forty', 'fifty', 'sixty', 'seventy', 'eighty', 'ninety' ];
        
        /* Array of scales as words */
        scales = [ '', 'thousand', 'million', 'billion', 'trillion', 'quadrillion', 'quintillion', 'sextillion', 'septillion', 'octillion', 'nonillion', 'decillion', 'undecillion', 'duodecillion', 'tredecillion', 'quatttuor-decillion', 'quindecillion', 'sexdecillion', 'septen-decillion', 'octodecillion', 'novemdecillion', 'vigintillion', 'centillion' ];
        
        /* Split user argument into 3 digit chunks from right to left */
        start = string.length;
        chunks = [];
        while( start > 0 ) {
            end = start;
            chunks.push( string.slice( ( start = Math.max( 0, start - 3 ) ), end ) );
        }
        
        /* Check if function has enough scale words to be able to stringify the user argument */
        chunksLen = chunks.length;
        if( chunksLen > scales.length ) {
            return '';
        }
        
        /* Stringify each integer in each chunk */
        words = [];
        for( i = 0; i < chunksLen; i++ ) {
            
            chunk = parseInt( chunks[i] );
            
            if( chunk ) {
                
                /* Split chunk into array of individual integers */
                ints = chunks[i].split( '' ).reverse().map( parseFloat );
            
                /* If tens integer is 1, i.e. 10, then add 10 to units integer */
                if( ints[1] === 1 ) {
                    ints[0] += 10;
                }
                
                /* Add scale word if chunk is not zero and array item exists */
                if( ( word = scales[i] ) ) {
                    words.push( word );
                }
                
                /* Add unit word if array item exists */
                if( ( word = units[ ints[0] ] ) ) {
                    words.push( word );
                }
                
                /* Add tens word if array item exists */
                if( ( word = tens[ ints[1] ] ) ) {
                    words.push( word );
                }
                
                /* Add 'and' string after units or tens integer if: */
                if( ints[0] || ints[1] ) {
                    
                    /* Chunk has a hundreds integer or chunk is the first of multiple chunks */
                    if( ints[2] || ! i && chunksLen ) {
                        words.push( and );
                    }
                
                }
                
                /* Add hundreds word if array item exists */
                if( ( word = units[ ints[2] ] ) ) {
                    words.push( word + ' hundred' );
                }
                
            }
            
        }
        
        return words.reverse().join( ' ' );
        
    }


// - - - - - Tests - - - - - -
function test(v) {
  var sep = ('string'==typeof v)?'"':'';
  console.log("numberToEnglish("+sep + v.toString() + sep+") = "+numberToEnglish(v));
}
test(2);
test(721);
test(13463);
test(1000001);
test("21,683,200,000,621,384");