document.getElementsByClassName = function(cl) {
    var retnode = [];
    var myclass = new RegExp('\\b'+cl+'\\b');
    var elem = this.getElementsByTagName('*');
    for (var i = 0; i < elem.length; i++) {
        var classes = elem[i].className;
        if (myclass.test(classes)) retnode.push(elem[i]);
    }
    return retnode;
}

var index_menu = document.getElementsByClassName("index_menu");
for(var k=0; k<index_menu.length; k++){
	index_menu[k].onmouseover=function(){
		this.className="index_menu_hover";

		}
	index_menu[k].onmouseout=function(){	
		this.className="index_menu";
		}
		
	}