為了兼容ie8以下的寫法

1.forEach

Array.prototype.myForEach = function (callback,context){context = context || window;if(Array.prototype.forEach) {this.forEach(callback,context);return;}//IE6-8下自己編寫回調函數執行的邏輯for(var i = 0,len = this.length; i < len;i++) {callback && callback.call(context,this[i],i,this);} } var qq = [1,2,3,4,5] qq.myForEach(function(item,index,arr){arr[index]+=1 }) console.log(qq)

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2.map

Array.prototype.mymap = function (callback,context){//判斷是否為ie8以下context = context || window;//是否有this指向if(Array.prototype.map){return this.map(callback,window);}var newArry=[]for (var i=0;i<this.length;i++){var val= callback.call(context,this[i],i,this)newArry[i]=val;}return newArry } var qq = [1,2,3,4,5] var arr1= qq.mymap(function(item,index,arr){return item+1 }) console.log(arr1)

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3.filter

Array.prototype.myfilter = function (callback,context){//判斷是否為ie8以下context = context || window;//是否有this指向if(Array.prototype.map){return this.map(callback,window);}var newArry=[]for (var i=0;i<this.length;i++){var val= callback.call(context,this[i],i,this)if(val){newArry.push(this[i])}}return newArry } var qq = [1,2,3,4,5] var arr1= qq.myfilter(function(item,index,arr){return item>=2 }) console.log(arr1)

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4.some

Array.prototype.mysome = function (callback,context){//判斷是否為ie8以下context = context || window;//是否有this指向if(Array.prototype.map){return this.some(callback,window);}for (var i=0;i<this.length;i++){var val= callback.call(context,this[i],i,this)if(val){return true;}}return false; } var qq = [1,2,3,4,5] var arr1= qq.mysome(function(item,index,arr){return item>=2 }) console.log(arr1)

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5.every

Array.prototype.myevery = function (callback,context){//判斷是否為ie8以下context = context || window;//是否有this指向if(Array.prototype.map){return this.every(callback,window);}for (var i=0;i<this.length;i++){var val= callback.call(context,this[i],i,this)if(!val){return false;}}return true; } var qq = [1,2,3,4,5] var arr1= qq.myevery(function(item,index,arr){return item>=1 }) console.log(arr1)

轉載于:https://www.cnblogs.com/city1995/p/7739250.html

總結

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