/* 方法的调用链 */

(function(){
    function _$(els){
        this.elements = [];
        for(var i=0,len = els.length ;i<len; ++i){
            var element = els[i];
            if (typeof element === 'string') {
                element = document.getElementById(element);
            }
            this.elements.push(element);
        }
    }
    _$.prototype = {
        each: function(){
            for( var i=0, len=this.elements.length;i<len; ++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(el){
                that.setStyle('display','block');
            });
            return this;
        },
        addEvent: function(){
            var add = function(el){
                if (window.addEventListtener) {
                    el.addEventListtener(type, fn, false);
                }
                else if (window.attachEvent) {
                    el.attachEvent('on'+type, fn);
                }
            };
            this.each(function(el){
                add(el);
            });
            return this;
        }
    };
    window.$ = function(){
        return new _$(arguments);
    };
})();

$(window).addEvent('load',function(){
    $('test-1','test-2').show().setStyle('color','red').addEvent('click',function(e){
        $(this).setStyle('color','green');
    });
});