Several (prototype) inheritance of JavaScript

Define Foo,bar

Where Bar inherits Foo

A is an instance of bar that contains the functions and properties of Foo and bar:

functionFoo (name) { This. Name =name;} Foo.prototype.myName=function() {    return  This. Name;};functionBar (Name,label) {Foo.call ( This, name);  This. Label =label;}//Here , we make a new ' Bar.prototype '//linked to ' Foo.prototype 'Bar.prototype = object.create (Foo.prototype);//Core Code//beware! Now ' Bar.prototype.constructor ' is gone,//And might need to being manually "fixed" If you ' re//In the habit of relying on such properties!Bar.prototype.myLabel=function() {    return  This. Label;};varA =NewBar ("A", "obj a"); A.myname (); //"a"A.mylabel ();//"obj a"

Where the core code is

Bar.prototype = Object.create (Foo.prototype);

We can still make the output unchanged by changing this line of code to the following, but the internal implementation is completely different.

1, bar.prototype = Foo.prototype;

Recommended Index: ★

Rating: Performing Bar.prototype.myLabel = ... Assignment statement will directly modify the Foo.prototype object itself, rather than the bar only with Foo

//1th TypeBar.prototype =Foo.prototype;a;//The output is as followsBar {name: ' A ', Label: ' obj a '}a.__proto__; //The output is as followsObject {myName:function, MyLabel:function, constructor:function}a.__proto__.__proto__; //The output is as followsObject {method:function, __definegetter__:function, __definesetter__:function, hasOwnProperty:function, __lookupgetter__:function...}

2, Bar.prototype = new Foo ();

Recommended Index: ★

Evaluation: The contents of the Foo function are likely to have side effects, and his operations will directly affect the offspring of Bar (), with disastrous consequences. As the following undefined

// 2nd Type New  // output The following Bar {name: "A", Label: "obj a"// outputs the following function  // output The following functionfunction}

3, object.setprototypeof (Bar.prototype,foo.prototype);

Recommendation Index: ★★★★★

Rating: Perfect, bar's constructor has not changed

Bar.prototype.constructor
function Bar (Name,label) {
Foo.call (this, name);
This.label = label;
}

// 3rd Type  // output The following Bar {name: "A", Label: "obj a"// outputs the following function function  // output The following functionfunction}

4, Bar.prototype = Object.create (Foo.prototype);

Recommendation Index: ★★★★

Evaluation: Bar.prototype itself constructor lost, go to prototype find, cause

Bar.prototype.constructor
function Foo (name) {
THIS.name = name;
}

// Original Bar.prototype =// output follows Bar {name: "A", Label: "Obj a"// output as follows  function// output as functionfunction}

Several (prototype) inheritance of JavaScript