类似jQuery的语法为何不起作用？

Question

(function(){
var W=window.W=window.$=function(selector){
return new W.core.init(selector);
};

W.core=W.prototype={
/*selector*/
init:function(els){
var elements=[];
for(var i=0,l=els.length;i<l;i++){
var element=arguments[i];
if(typeof element=='string'){
element=document.getElementById(element);
}
}
if(arguments.length===1){
return element;
}
elements.push(element);
return elements;
},
each:function(fn){
for(var i=0,l=this.elements.length;i<l;i++){
fn.call(this,this.elements[i]);
}
return this;
},
setStyle:function(prop,val){
this.each(function(el){
el.style[prop]=val;
});
return this;
},
show:function(){
var that=this;
this.each(function(){
that.setStyle("display","");
});
return this;
},
hide:function(){
var that=this;
this.each(function(){
that.setStyle("display","none");
});
return this;
}
}
W.core.init.prototype=W.core;
})();
然后调用此js
<script type="text/javascript">
window.onload=function(){
$('p').hide();
}
</script>为何链式调用不起作用？

Answer 1

jquery不是“形”像就可以了，你看看你hide里this指向哪里？

Answer 2

this指向哪里？
 回复内容太短了！ 

Answer 3

        // 让init返回当前实例
        init:function(els){
            this.elements=[];
            for(var i=0,l=els.length;i<l;i++){
                var element=arguments[i];
                if(typeof element=='string'){
                    element=document.getElementById(element);
                }
            }        
            this.elements.push(element);
            return this;
        },