jQuery 简单实现

/**
 * JQuery 基础功能
 * @param  {[type]} ) {var $ [description] }
 * @return {[type]}   [description]
 */
var $ = (function () { 
    var $ = function (selector, context) { 
        return new $.prototype.init(selector, context); 
    };

    $.prototype.init = function (selector, ctx) {
        if(typeof selector === 'string'){
            var context = ctx || document; 
            var nodeList = context.querySelectorAll(selector); 
            this.length = nodeList.length; 
            for (var i = 0; i < this.length; i++) { 
                this[i] = nodeList[i]; 
            } 

        }else if(typeof selector === 'object'){
            this[0] = selector;
            this.length = 1;
        }
        return this; 
    };

    $.prototype.each = function (callback, args) { 
        var length = this.length, i = 0; 

        while (i < length) { 
            callback.call(this[i], args);
            i += 1; 
        } 

        return this; 
    };

    $.prototype.css = function(arg1, arg2){

        if(typeof arg1 === 'string' && !arg2){
            return getEleStyle(this[0])[arg1];
        }

        var sty_obj = arg1;
        if(typeof arg1 !== 'object' && arg2){
            sty_obj = {};
            sty_obj[arg1] = arg2;
        }

        this.each(function(){
            for(var sty_name in sty_obj){
                var sty = getEleStyle(this);
                sty[sty_name] = sty_obj[sty_name];
                this.setAttribute('style', JSON.stringify(sty).replace(/[{}"]/g, '').replace(/[,]/g, ";") );
            }
        });

        return this;
    };

    $.prototype.addClass = function(arg1){
        this.each(function(){
            this.setAttribute('class', (this.getAttribute('class')||'') + ' ' + arg1 );
        });
        return this;
    };

    $.prototype.removeClass = function(arg1){
        this.each(function(){
            this.setAttribute('class', (this.getAttribute('class')||'').replace(arg1, '') );
        });
        return this;
    };

    $.prototype.attr = function(arg1, arg2){

        if(!arg2 && typeof arg1 === 'string'){
            return this[0].getAttribute(arg1) || '';
        }

        var attr_obj = arg2 ? {arg1:arg2} : arg1;

        this.each(function(){
            for(var attr_name in attr_obj){
                this.setAttribute(attr_name, attr_obj[attr_name]);
            }
        });

        return this;
    };

    $.prototype.html = function (arg1) { 
        if (typeof arg1 == 'string') { 
            this.each(function () { 
                this.innerHTML = arg1; 
            }); 
            return this; 
        } else { 
            return this[0].innerHTML; 
        } 
    };

    $.prototype.remove = function(){
        this.each(function(){
            this.parentNode.removeChild(this);
        });     
    };
    $.prototype.append = function(arg1){
        if(typeof arg1 === 'object'){

            this.each(function(){
                this.appendChild(arg1);
            });

        }else if(typeof arg1 === 'string'){

            this.each(function(){
                this.innerHTML = arg1;
            });
        }
        return this;
    };

    $.prototype.bind = function(event, hander){
        if (this[0].addEventListener) {  

            this.each(function(){
                this.addEventListener(event, hander);
            });

        } else if (this[0].attachEvent) {                 
            this.each(function(){
                this.attachEvent("on" + event, hander);
            });
        }
    };

    $.prototype.init.prototype = $.prototype;

    function getEleStyle (element){
        var style = {};
        var style_attr =  element.getAttribute('style');
        if(style_attr){
            var style_arr = style_attr.split(';');
            for(var item = 0; item < style_arr.length; item ++){
                var item_val = style_arr[item].split(':');
                style[item_val[0]] = item_val[1];
            }
        }
        return style;
    }
    return $; 
})();