How to getElementByClass instead of GetElementById with JavaScript?


I'm trying to toggle the visibility of certain DIV elements on a website depending on the class of each DIV. I'm using a basic JavaScript snippet to toggle them. The problem is that the script only uses getElementById, as getElementByClass is not supported in JavaScript. And unfortunately I do have to use class and not id to name the DIVs because the DIV names are dynamically generated by my XSLT stylesheet using certain category names.

I know that certain browsers now support getElementByClass, but since Internet Explorer doesn't I don't want to go that route.

I've found scripts using functions to get elements by class (such as #8 on this page: http://www.dustindiaz.com/top-ten-javascript/), but I can't figure out how to integrate them with with my toggle script.

Here's the HTML code. The DIVs themselves are missing since they are generated on page load with XML/XSLT.

Main Question: How do I get the below Toggle script to get Element by Class instead of get Element by ID?

<html>

<head>

<!--This is the TOGGLE script-->
<script type="text/javascript">
<!--
    function toggle_visibility(id) {
       var e = document.getElementById(id);
       if(e.style.display == 'block')
          e.style.display = 'none';
       else
          e.style.display = 'block';
    }
//-->
</script>

</head>

<!--the XML/XSLT page contents will be loaded here, with DIVs named by Class separating dozens of li's-->

<a href="#" onclick="toggle_visibility('class1');">Click here to toggle visibility of class 1 objects</a>

<a href="#" onclick="toggle_visibility('class2');">Click here to toggle visibility of class 2 objects</a>

</body>
</html>

Modern browsers have support for document.getElementsByClassName. You can see the full breakdown of which vendors provide this functionality at caniuse. If you're looking to extend support into older browsers, you may want to consider a selector engine like that found in jQuery or a polyfill.

Older Answer

You'll want to check into jQuery, which will allow the following:

$(".classname").hide(); // hides everything with class 'classname'

Google offers a hosted jQuery source-file, so you can reference it and be up-and-running in moments. Include the following in your page:

<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js"></script>
<script type="text/javascript">
  $(function(){
    $(".classname").hide();
  });
</script>

The getElementsByClassName method is now natively supported by the most recent versions of Firefox, Safari, Chrome, IE and Opera, you could make a function to check if a native implementation is available, otherwise use the Dustin Diaz method:

function getElementsByClassName(node,classname) {
  if (node.getElementsByClassName) { // use native implementation if available
    return node.getElementsByClassName(classname);
  } else {
    return (function getElementsByClass(searchClass,node) {
        if ( node == null )
          node = document;
        var classElements = [],
            els = node.getElementsByTagName("*"),
            elsLen = els.length,
            pattern = new RegExp("(^|\\s)"+searchClass+"(\\s|$)"), i, j;

        for (i = 0, j = 0; i < elsLen; i++) {
          if ( pattern.test(els[i].className) ) {
              classElements[j] = els[i];
              j++;
          }
        }
        return classElements;
    })(classname, node);
  }
}

Usage:

function toggle_visibility(className) {
   var elements = getElementsByClassName(document, className),
       n = elements.length;
   for (var i = 0; i < n; i++) {
     var e = elements[i];

     if(e.style.display == 'block') {
       e.style.display = 'none';
     } else {
       e.style.display = 'block';
     }
  }
}

document.getElementsByClassName('CLASSNAME')[0].style.display = 'none';

Acyually by using getElementsByClassName, it returns an array of multiple classes. Because same class name could be used in more than one instance inside same HTML page. We use array element id to target the class we need, in my case, it's first instance of the given class name.So I've used [0]


Use it to access class in Javascript.

<script type="text/javascript">
var var_name = document.getElementsByClassName("class_name")[0];
</script>

adding to CMS's answer, this is a more generic approach of toggle_visibility I've just used myself:

function toggle_visibility(className,display) {
   var elements = getElementsByClassName(document, className),
       n = elements.length;
   for (var i = 0; i < n; i++) {
     var e = elements[i];

     if(display.length > 0) {
       e.style.display = display;
     } else {
       if(e.style.display == 'block') {
         e.style.display = 'none';
       } else {
         e.style.display = 'block';
       }
     }
  }
}

My solution:

First create "<style>" tags with an ID.

<style id="YourID">
    .YourClass {background-color:red}
</style>

Then, I create a function in JavaScript like this:

document.getElementById('YourID').innerHTML = '.YourClass {background-color:blue}'

Worked like a charm for me.


Append IDs at the class declaration

.aclass, #hashone, #hashtwo{ ...codes... }
document.getElementById( "hashone" ).style.visibility = "hidden";