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用apply把document當作this傳入getId函數，幫助“修正”this;

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

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類型判斷

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);};

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自定義事件（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;},// 觸發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;},// 刪除removeEvent: function(type, fn) {var arrayEvent = this._listeners[type];if (typeof type === "string" && arrayEvent instanceof Array) {if (typeof fn === "function") {// 清除當前type類型事件下對應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 {// 如果僅僅參數type, 或參數fn邪魔外道，則所有type類型事件清除delete this._listeners[type];}}return this;} };

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自定義事件（二）：

//自定義事件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;};//添加監聽事件，并緩存_listen = function (key,fn,cache) { if(!cache[key]){cache[key]=[];}cache[key].push(fn);};//移除監聽_remove=function (key,cache,fn) { if(cache[key]){ //如果存在該監聽事件if(fn){ //如果存在回調函數for (var i = cache[key].length; i >=0; i--){if(cache[key][i]===fn){cache[key].splice(i,1); //移除此回調函數 }}}else{cache[key]=[]; //清除此事件（為什么存在回調函數時不執行此步驟，奇怪） }}};//觸發事件_trigger=function () { var cache = _shift.call(arguments), //第一個參數是cachekey = _shift.call(arguments), //第二個參數是keyargs = arguments,_self = this,ret,stack= cache[key];if(!stack || !stack.length){ //沒有回調函數則直接返回return;}return each(stack, function () { //執行所有的回調函數return this.apply(_self,args);});};//創建事件的實例_create=function (namespace) { var namespace = namespace || _default;var cache ={},offlineStack=[], //離線事件ret={listen:function (key,fn,last) { _listen(key,fn,cache);if(offlineStack===null){return;}if(last==='last'){offlineStack.length && offlineStack.pop()(); //如果是最后一個離線事件，觸發此離線事件并移除此事件}else{each(offlineStack,function(){ //如果是多個離線事件，并遍歷觸發this();});}offlineStack = null; 清空離線事件},//執行一次監聽事件one:function (key,fn,last) { _remove(key,cache); //此緩存中移除此事件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); //將cache緩存添加到arguments參數集合中args=arguments;fn=function(){return _trigger.apply(_self,args);};if(offlineStack){return offlineStack.push(fn);}return fn(); //觸發事件 }};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;})();

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方法綁定：

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)) )} }

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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;} }

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轉載于:https://www.cnblogs.com/jasonoiu/p/Classic-JS.html

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