javascript 繼承實現

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JavaScript進階程式設計讀書筆記

這本書繼承的實現列舉了好幾種，裡面有兩種是比較靠譜的。

1 組合繼承

//父建構函式function Super(name) {    this.name = name;    this.colors = [‘black‘, ‘red‘];}
Super.prototype.getName = function() {    return this.name;}

//子建構函式function Sub(name, age) {    Super.call(this, name);    this.age = age;}
//把Sub的原型修改為Super的執行個體，就能繼承Super.prototype中的屬性和方法了，
//這樣存在的問題是：把name和colors屬性也添加到Sub.prototype中了，這部分對執行個體是不可見的，
//因為調用new Sub()產生執行個體時，會把name和colors添加為執行個體屬性Sub.prototype = new Super();Sub.prototype.getAge = function(){    return this.age;}
//前面修改Sub.prototype時，導致Sub.prototype.constructor指向了Super,所以要修改回來

Sub.prototype.constructor = Sub; 
var ins1 = new Sub(‘mengxb‘, 28);

2 寄生組合式繼承

function Object(o) {    function F() {};    F.prototype = o;    return new F();}function inheritPrototype(sub, super) {    var prototype = Object(super.prototype);    sub.prototype = prototype;    sub.prototype.construtor = sub;}function Super(name) {    this.name = name;    this.colors = [‘black‘, ‘red‘];}Super.prototype.getName = function() {    return this.name;}function Sub(name, age) {    Super.call(this, name);    this.age = age;}inheritPrototype(Sub, Super);Sub.prototype.getAge = function(){    return this.age;}

 

javascript 繼承實現