How to inherit an Object in JavaScript

最新推荐文章于 2020-09-14 21:40:04 发布

原创最新推荐文章于 2020-09-14 21:40:04 发布 · 911 阅读

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本文介绍了JavaScript中实现继承的多种方法，包括使用原型链、直接复制属性以及利用构造函数等方式，并对比了不同方法的特点与局限性。

We can use the prototype chain to implement the inheritance of methods from a super class.

The method most people use:
```
function inherit(sub, supper){
    var subProto = sub.prototype = new supper();
    subProto.constructor = sub;
}
```
Note: this will always call the supper's constructor and it is just a waste in some way.

The method not really inheritance:

function inherit(sub, supper){
    var subProto = sub.prototype, supProto = supper.prototype;
    for(var i in supProto){
        if(!subProtp[i]) subProto[i] = supProto[i];
    }
}

Note: the result of new Sub() instanceof Supper is false.

The method derives from method 1:

function inherit(sub, supper){
    var subProto = sub.prototype;
    subProto = Object.create(supper.prototype);
    subProto.constructor = sub;
}
function inherit(sub, supper){
    var subProto = sub.prototype;
    var F = function(){};
    F.prototype = supper.prototype;    
    subProto = new F();
    subProto.constructor = sub;
}

The method simplest but IE doesn't support:

function inherit(sub, supper){
    sub.prototype.__proto__ = supper.prototype;
}