最近用到的一些封装函数~

function getElementsByClassName(obj, cls){
var elements=obj.getElementsByTagName("*");
var result=[];
for(var i=0;i<elements.length;i++){
if(elements[i].className==cls){
result.push(elements[i]);
}
}
return result;
}

function hasClass(obj, cls){
return obj.className.match(new RegExp("(\\s|^)"+cls+"(\\s|$)"));
}

function removeClass(obj, cls){
if(hasClass(obj,cls)){
obj.className=obj.className.replace(new RegExp('(\\s|^)'+cls+'(\\s|$)'),'');
}
}

function addClass(obj,cls){
if(!hasClass(obj,cls)){
obj.className+=" "+cls;
}
}

var get_body_w=function(){
return document.body.offsetWidth;
}
var get_body_h=function(){
return document.body.offsetHeight;
}

function addEvent(obj , event , fn){
if (obj.addEventListener) {
obj.addEventListener(event,fn)
}else if(obj.attachEvent){
obj.attachEvent('on'+event,fn)
}
}