Best way to track onchange as-you-type in input type=“text”?

Update:

See Another answer (2015).

Original 2009 Answer:

So, you want the onchange event to fire on keydown, blur, and paste? That's magic.

If you want to track changes as they type, use "onkeydown". If you need to trap paste operations with the mouse, use "onpaste" (IE, FF3) and "oninput" (FF, Opera, Chrome, Safari¹).

¹_{Broken for <textarea> on Safari. Use textInput instead}

These days listen for oninput. It feels like onchange without the need to lose focus on the element. It is HTML5.

It’s supported by everyone (even mobile), except IE8 and below. For IE add onpropertychange. I use it like this:

const $source = document.querySelector('#source');
const $result = document.querySelector('#result');

const typeHandler = function(e) {
  $result.innerHTML = e.target.value;
}

$source.addEventListener('input', typeHandler) // register for oninput
$source.addEventListener('propertychange', typeHandler) // for IE8
// $source.addEventListener('change', typeHandler) // fallback for Firefox for <select><option>, for <input> oninput is enough

<input id="source" />
<div id="result"></div>

Below code works fine for me with Jquery 1.8.3

HTML : <input type="text" id="myId" />

Javascript/JQuery:

$("#myId").on('change keydown paste input', function(){
      doSomething();
});

Javascript is unpredictable and funny here.

• onchange occurs only when you blur the textbox
• onkeyup & onkeypress doesn't always occur on text change
• onkeydown occurs on text change (but cannot track cut & paste with mouse click)
• onpaste & oncut occurs with keypress and even with the mouse right click.

So, to track the change in textbox, we need onkeydown, oncut and onpaste. In the callback of these event, if you check the value of the textbox then you don't get the updated value as the value is changed after the callback. So a solution for this is to set a timeout function with a timeout of 50 mili-seconds (or may be less) to track the change.

This is a dirty hack but this is the only way, as I researched.

Here is an example. http://jsfiddle.net/2BfGC/12/

onkeyup happens after you type for example I press t when I lift the finger the action happens but on keydown the action happens before I digit the character t

Hope this is helpful for someone.

So onkeyup is better for when you want to send what you just typed now.

I had a similar requirement (twitter style text field). Used onkeyup and onchange. onchange actually takes care of mouse paste operations during lost focus from the field.

[Update] In HTML5 or later, use oninput to get real time character modification updates, as explained in other answers above.

If you use ONLY Internet Explorer, you can use this:

<input type="text" id="myID" onpropertychange="TextChange(this)" />

<script type="text/javascript">
    function TextChange(tBox) {
        if(event.propertyName=='value') {
            //your code here
        }
    }
</script>

Hope that helps.

I think in 2018 it's better to use the input event.

-

As the WHATWG Spec describes (https://html.spec.whatwg.org/multipage/indices.html#event-input-input):

Fired at controls when the user changes the value (see also the change event)

-

Here's an example of how to use it:

<input type="text" oninput="handleValueChange()">

there is a quite near solution (do not fix all Paste ways) but most of them:

It works for inputs as well as for textareas:

<input type="text" ... >
<textarea ... >...</textarea>

Do like this:

<input type="text" ... onkeyup="JavaScript: ControlChanges()" onmouseup="JavaScript: ControlChanges()" >
<textarea ... onkeyup="JavaScript: ControlChanges()" onmouseup="JavaScript: ControlChanges()" >...</textarea>

As i said, not all ways to Paste fire an event on all browsers... worst some do not fire any event at all, but Timers are horrible to be used for such.

But most of Paste ways are done with keyboard and/or mouse, so normally an onkeyup or onmouseup are fired after a paste, also onkeyup is fired when typing on keyboard.

Ensure yor check code does not take much time... otherwise user get a poor impresion.

Yes, the trick is to fire on key and on mouse... but beware both can be fired, so take in mind such!!!

Please, judge next approach using JQuery:

HTML:

<input type="text" id="inputId" />

Javascript(JQuery):

$("#inputId").keyup(function(){
        $("#inputId").blur();
        $("#inputId").focus();
});

$("#inputId").change(function(){
        //do whatever you need to do on actual change of the value of the input field
});

"input" worked for me.

var searchBar  = document.getElementById("searchBar");
searchBar.addEventListener("input", PredictSearch, false);

You could use the keydown, keyup and keypress events as well.

To track each try this example and before that completely reduce cursor blink rate to zero.

<body>
//try onkeydown,onkeyup,onkeypress
<input type="text" onkeypress="myFunction(this.value)">
<span> </span>
<script>
function myFunction(val) {
//alert(val);
var mySpan = document.getElementsByTagName("span")[0].innerHTML;
mySpan += val+"<br>";
document.getElementsByTagName("span")[0].innerHTML = mySpan;
}
</script>

</body>

onblur : event generates on exit

onchange : event generates on exit if any changes made in inputtext

onkeydown: event generates on any key press (for key holding long times also)

onkeyup : event generates on any key release

onkeypress: same as onkeydown (or onkeyup) but won't react for ctrl,backsace,alt other

2018 here, this is what I do:

$(inputs).on('change keydown paste input propertychange click keyup blur',handler);

If you can point out flaws in this approach, I would be grateful.

Robert Siemer addEventListener is not supported in IE8 .

"Older versions of IE supported an equivalent, proprietary EventTarget.attachEvent() method." https://developer.mozilla.org/it/docs/Web/API/Element/addEventListener

Method 1: Add an event listener for input:

element.addEventListener("input", myFunction);

Method 2: Define the oninput property with JavaScript:

element.oninput = function()
{
    myFunction();
};

Method 3: Define the oninput property with HTML:

<input type="text" oninput="myFunction();">

strong text

const source = document.getElementById('source');
const result = document.getElementById('result');

const inputHandler = function(e) {
  result.innerHTML = e.target.value;
}

source.addEventListener('input', inputHandler);
source.addEventListener('propertychange', inputHandler); // for IE8
// Firefox/Edge18-/IE9+ don’t fire on <select><option>
// source.addEventListener('change', inputHandler); 

<input id="source">
<div id="result"></div>