javascript document.getElementsByClassName compatibility with IE

Question

What is the best method to retrieve an array of elements that have a certain class?

I would use document.getElementsByClassName but IE does not support it.

So I tried Jonathan Snook's solution:

function getElementsByClassName(node, classname) {     var a = [];     var re = new RegExp('(^| )'+classname+'( |$)');     var els = node.getElementsByTagName("*");     for(var i=0,j=els.length; i<j; i++)         if(re.test(els[i].className))a.push(els[i]);     return a; } var tabs = document.getElementsByClassName(document.body,'tab'); 

...but IE still says:

Object doesn't support this property or method

Any ideas, better methods, bug fixes?

I would prefer not to use any solutions involving jQuery or other "bulky javascript".

Update:

I got it to work!

As @joe mentioned the function is not a method of document.

So the working code would look like this:

function getElementsByClassName(node, classname) {     var a = [];     var re = new RegExp('(^| )'+classname+'( |$)');     var els = node.getElementsByTagName("*");     for(var i=0,j=els.length; i<j; i++)         if(re.test(els[i].className))a.push(els[i]);     return a; } var tabs = getElementsByClassName(document.body,'tab'); 

...Also if you only need IE8+ support then this will work:

if(!document.getElementsByClassName) {     document.getElementsByClassName = function(className) {         return this.querySelectorAll("." + className);     };     Element.prototype.getElementsByClassName = document.getElementsByClassName; } 

Use it just like normal:

var tabs = document.getElementsByClassName('tab'); 

Answer 1

It's not a method of document:

function getElementsByClassName(node, classname) {     var a = [];     var re = new RegExp('(^| )'+classname+'( |$)');     var els = node.getElementsByTagName("*");     for(var i=0,j=els.length; i<j; i++)         if(re.test(els[i].className))a.push(els[i]);     return a; }  tabs = getElementsByClassName(document.body,'tab');  // no document 

Answer 2

you may create the function for older browsers

if (typeof document.getElementsByClassName!='function') {     document.getElementsByClassName = function() {         var elms = document.getElementsByTagName('*');         var ei = new Array();         for (i=0;i<elms.length;i++) {             if (elms[i].getAttribute('class')) {                 ecl = elms[i].getAttribute('class').split(' ');                 for (j=0;j<ecl.length;j++) {                     if (ecl[j].toLowerCase() == arguments[0].toLowerCase()) {                         ei.push(elms[i]);                     }                 }             } else if (elms[i].className) {                 ecl = elms[i].className.split(' ');                 for (j=0;j<ecl.length;j++) {                     if (ecl[j].toLowerCase() == arguments[0].toLowerCase()) {                         ei.push(elms[i]);                     }                 }             }         }         return ei;     } }