Javascript GetElementsByClass

today, i have any reason to search HTML element by class name but javascript is not have support function. so i found somethings in the internet but not as good as i need. but i can modify it as i want. so it's be like this.

String.prototype.trim = function() { return this.replace(/^\s+|\s+$/g, ''); };

Document.prototype.getElementsByClass = function( searchClass, tagName) {

if (tagName == null) tagName = '*';

var el = new Array();

var tags = this.getElementsByTagName(tagName);

var tcl = " "+searchClass.trim()+" ";

for(i=0,j=0; i

var test = " " + tags[i].className + " ";

if (test.indexOf(tcl) != -1)

el[j++] = tags[i];

}

return el;

};