JS的封装函数

1.封装hasPubProperty公有属性

Object.prototype.hasPubProperty = function (key) {
 if ((key) in this && !this.hasOwnProperty(key)) {
 return true;
 }
 return false;
}
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2.封装myPop，去掉末尾项

Array.prototype.myPop = function () {
 let temp = this[this.length - 1];
 this.length--;
 return temp;
 }
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3.封装myUnique数组去重

Object.prototype.hasPubProperty = function (key) {
 var obj = {};
 for (var i = 0; i < this.length; i++) {
 if (obj.hasOwnProperty(this[i])) {
 this.splice(i, 1);
 i--;
 } else {
 obj[this[i]] = this[i]
 }
 }
 }
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4.封装myPop去除最后数组一项

 Array.prototype.myPop = function () {
 let temp = this[this.length - 1];
 this.length--;
 return temp;
 }
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5.封装myPush在末尾项增加

 Array.prototype.myPush = function () {
 var l = ary.length;
 for (var i = 0; i < l; i++) {
 this[this.length] = ary[i];
 }
 return this;
 }
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6.封装myCall方法等同于call

Function.prototype.myCall = function myCall(context, ...arg) {
 context = context || window;
 let a = Symbol();
 context[a] = this;
 let res = context[a](...arg);
 delete context[a];
 return res;
 }
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7.封装myApply方法等同于apply

Function.prototype.myApply = function myApply(context, arg) {
 arg = arg || [];
 context = context || window;
 let a = Symbol();
 context[a] = this;
 let res = context[a](...arg);
 delete context[a];
 return res;
 }
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8.封装myBind方法等同于bind

Function.prototype.myBind = function (context, ...arg) {
 var _this = this;
 return function (...ary) {
 return _this.apply(context, arg.concat(ary))
 }
 }
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9.封装myNew方法等同于new

function myNew(classN, ...arg) {
 var obj = {};
 obj.__proto__ = Person.prototype;
 var res = Person.call(obj, ...arg)
 return typeof res === 'object' ? res : obj;
 }
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10.封装myInstance方法等同于instanceof

function myInstance(temp, classN) {
 let str = typeof temp;
 if (str !== 'Object' && str !== 'Function') return false;
 var left = temp.__proto__,
 right = classN.prototype;
 while (left) {
 if (left === right) return true;
 left = left.__proto__;
 }
 return false
 }
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11.封装plus和minus方法

Number.prototype.plus = function (a) {
 return this + a;
 }
Number.prototype.minus = function (a) {
 return this - a;
 }
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12.封装一个判断数据类型的方法getType

Object.prototype.getType = function () {
 var str = this.constructor.toString();
 str = str.slice(9, str.indexOf('('));
 return str.toLowerCase();
 }
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13.封装myReverse方法等同于reverse

Array.prototype.myReverse = function () {
 for (var i = 0; i < this.length / 2; i++) {
 let temp = this[i];
 this[i] = this[this.length - 1 - i];
 this[this.length - 1 - i] = temp;
 }
 return this;
 }
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14.获取数组中的最大值

Array.prototype.max = function () {
 // 三种任选其一
 return this.sort((a, b) => b - a)[0];
 return Math.max(...this);
 return Math.max.apply(Math,this);
 }
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15.求数组中的平均值

 Array.prototype.average = function(){
 return eval(this.join('+'))/this.length;
 }