How to implement inheritance in javascript (code)-JS Tutorial-php.cn

How to implement inheritance in javascript (code)

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Release： 2018-08-07 17:34:55

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The content this article brings to you is about the implementation method (code) of JavaScript inheritance. It has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

There are many ways to implement inheritance in JS. The following are the more recommended methods. You can learn about other inheritance methods:

function object(o) {
    function F() {}
    F.prototype = o;
    return new F();
}

function inheritPrototype(subType, superType) {
    var newObj = object(superType.prototype);
    newObj.constructor = subType;
    subType.prototype = newObj;
}

function People() {
    this.cls = 'people';
}

People.prototype.say = function(name) {
    name = name || this.cls;
    console.log('My class is '+ name);
}

function Student() {
    People.call(this);
    this.type = 'student';
}

inheritPrototype(Student, People);

Student.prototype.goToSchool = function() {
    console.log('I go to school every day.');
}

// 测试
var stu = new Student();

console.log('class: ' + stu.cls); // class: people
console.log('type: ' + stu.type); // type: student
stu.say(); // My class is people
stu.goToSchool (); // I go to school every day.

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In fact, javascript has provided a simpler Implementation method, there is no need to reinvent the wheel here, and the method is not perfect, MDN example:

// Shape - 父类(superclass)
function Shape() {
  this.x = 0;
  this.y = 0;
}

// 父类的方法
Shape.prototype.move = function(x, y) {
  this.x += x;
  this.y += y;
  console.info('Shape moved.');
};

// Rectangle - 子类(subclass)
function Rectangle() {
  Shape.call(this); // call super constructor.
}

// 子类续承父类
Rectangle.prototype = Object.create(Shape.prototype);
Rectangle.prototype.constructor = Rectangle;

var rect = new Rectangle();

console.log('Is rect an instance of Rectangle?',
  rect instanceof Rectangle); // true
console.log('Is rect an instance of Shape?',
  rect instanceof Shape); // true
rect.move(1, 1); // Outputs, 'Shape moved.'

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If you want to inherit multiple objects, you can use the mixing method:

function MyClass() {
     SuperClass.call(this);
     OtherSuperClass.call(this);
}

// 继承一个类
MyClass.prototype = Object.create(SuperClass.prototype);
// 混合其它
Object.assign(MyClass.prototype, OtherSuperClass.prototype);
// 重新指定constructor
MyClass.prototype.constructor = MyClass;

MyClass.prototype.myMethod = function() {
     // do a thing
};

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