经典JS

 

用apply把document当作this传入getId函数，帮助“修正”this;

document.getElementById = (function (func) {return function () {return func.apply(document, arguments);}
})(document.getElementById);//调用
var getId = document.getElementById;
var div = getId('div2');

 

类型判断

var Type = {};for (var i = 0, type; type = ['String', 'Array', 'Number'][i++];) {(function (type) {Type['is' + type] = function (obj) {return Object.prototype.toString.call(obj) === '[object ' + type + ']';}})(type);};

 

自定义事件（一）：

var Event = {_listeners: {},    // 添加addEvent: function(type, fn) {if (typeof this._listeners[type] === "undefined") {this._listeners[type] = [];}if (typeof fn === "function") {this._listeners[type].push(fn);}    return this;},// 触发fireEvent: function(type) {var arrayEvent = this._listeners[type];if (arrayEvent instanceof Array) {for (var i=0, length=arrayEvent.length; i<length; i+=1) {if (typeof arrayEvent[i] === "function") {arrayEvent[i]({ type: type });    }}}    return this;},// 删除removeEvent: function(type, fn) {var arrayEvent = this._listeners[type];if (typeof type === "string" && arrayEvent instanceof Array) {if (typeof fn === "function") {// 清除当前type类型事件下对应fn方法for (var i=0, length=arrayEvent.length; i<length; i+=1){if (arrayEvent[i] === fn){this._listeners[type].splice(i, 1);break;}}} else {// 如果仅仅参数type, 或参数fn邪魔外道，则所有type类型事件清除delete this._listeners[type];}}return this;}
};

 

自定义事件（二）：

//自定义事件var Event=(function () { var global=this,Event,_default='default';Event=function () { var _listen,_trigger,_remove,_slice=Array.prototype.slice,_shift=Array.prototype.shift,_unshift=Array.prototype.unshift,namespaceCache={},_create,find,each=function (ary,fn) { var ret;for (var i = 0, l=ary.length; i < l; i++){var n=ary[i];ret=fn.call(n,i,n);}return ret;};//添加监听事件，并缓存_listen = function (key,fn,cache) { if(!cache[key]){cache[key]=[];}cache[key].push(fn);};//移除监听_remove=function (key,cache,fn) { if(cache[key]){ //如果存在该监听事件if(fn){ //如果存在回调函数for (var i = cache[key].length; i >=0; i--){if(cache[key][i]===fn){cache[key].splice(i,1); //移除此回调函数
                             }}}else{cache[key]=[]; //清除此事件（为什么存在回调函数时不执行此步骤，奇怪）
                      }}};//触发事件_trigger=function () { var cache = _shift.call(arguments), //第一个参数是cachekey = _shift.call(arguments),  //第二个参数是keyargs = arguments,_self = this,ret,stack= cache[key];if(!stack || !stack.length){ //没有回调函数则直接返回return;}return each(stack, function () { //执行所有的回调函数return this.apply(_self,args);});};//创建事件的实例_create=function (namespace) { var namespace = namespace || _default;var cache ={},offlineStack=[], //离线事件ret={listen:function (key,fn,last) { _listen(key,fn,cache);if(offlineStack===null){return;}if(last==='last'){offlineStack.length && offlineStack.pop()(); //如果是最后一个离线事件，触发此离线事件并移除此事件}else{each(offlineStack,function(){ //如果是多个离线事件，并遍历触发this();});}offlineStack = null; 清空离线事件},//执行一次监听事件one:function (key,fn,last) { _remove(key,cache); //此缓存中移除此事件this.listen(key,fn,last); //添加此事件
                              },remove:function (key,fn) { _remove(key,cache,fn);},trigger:function () { var fn,args,_self=this;_unshift.call(arguments,cache); //将cache缓存添加到arguments参数集合中args=arguments;fn=function(){return _trigger.apply(_self,args);};if(offlineStack){return offlineStack.push(fn);}return fn(); //触发事件
                                }};return namespace ?(namespaceCache[namespace] ? namespaceCache[namespace]:namespaceCache[namespace]= ret ) 
                                    :ret;};return {create: _create,one: function (key, fn, last) {var event = this.create();event.one(key, fn, last);},remove: function (key, fn) {var event = this.create();event.remove(key, fn);},listen: function (key, fn, last) {var event = this.create();event.listen(key, fn, last);},trigger: function () {var event = this.create();event.trigger.apply(this,arguments);}};}();return Event;})();

 

方法绑定：

Function.prototype.bind = function () {var self = this,context  = [].shift.call(arguments),args     = [].slice.call(arguments);return function () {return self.apply( context, [].concat.call(args, [].slice.call(arguments)) )} 
}

 

AOP：

Function.prototype.before = function(beforefn) {var _self = this;return function() {beforefn.apply(this, arguments);return _self.apply(this, arguments);}
}Function.prototype.after = function(afterfn) {var _self = this;return function() {var ret = _self.apply(this, arguments);afterfn.apply(this, arguments);return ret;}
}