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原生js如何实现继承

2026-04-04 16:48:09JavaScript

原型链继承

通过将子类的原型指向父类的实例实现继承。子类实例通过原型链访问父类属性和方法。

function Parent() {
  this.name = 'parent';
}
Parent.prototype.sayName = function() {
  console.log(this.name);
};

function Child() {}
Child.prototype = new Parent();

const child = new Child();
child.sayName(); // 'parent'

构造函数继承

在子类构造函数中调用父类构造函数，使用call或apply方法改变this指向。

function Parent(name) {
  this.name = name;
}
Parent.prototype.sayName = function() {
  console.log(this.name);
};

function Child(name, age) {
  Parent.call(this, name);
  this.age = age;
}

const child = new Child('child', 10);
console.log(child.name); // 'child'
console.log(child.age); // 10
child.sayName(); // TypeError

组合继承

结合原型链继承和构造函数继承，既能继承父类原型方法，又能向父类构造函数传参。

function Parent(name) {
  this.name = name;
}
Parent.prototype.sayName = function() {
  console.log(this.name);
};

function Child(name, age) {
  Parent.call(this, name);
  this.age = age;
}
Child.prototype = new Parent();
Child.prototype.constructor = Child;

const child = new Child('child', 10);
child.sayName(); // 'child'
console.log(child.age); // 10

原型式继承

使用Object.create()方法基于现有对象创建新对象，无需定义构造函数。

const parent = {
  name: 'parent',
  sayName: function() {
    console.log(this.name);
  }
};

const child = Object.create(parent);
child.name = 'child';
child.sayName(); // 'child'

寄生式继承

在原型式继承基础上增强对象，添加额外方法。

function createChild(parent) {
  const child = Object.create(parent);
  child.sayAge = function() {
    console.log(this.age);
  };
  return child;
}

const parent = {
  name: 'parent'
};
const child = createChild(parent);
child.age = 10;
child.sayAge(); // 10

寄生组合式继承

最理想的继承方式，只调用一次父类构造函数，避免创建多余属性，同时保持原型链。

原生js如何实现继承

function inheritPrototype(child, parent) {
  const prototype = Object.create(parent.prototype);
  prototype.constructor = child;
  child.prototype = prototype;
}

function Parent(name) {
  this.name = name;
}
Parent.prototype.sayName = function() {
  console.log(this.name);
};

function Child(name, age) {
  Parent.call(this, name);
  this.age = age;
}
inheritPrototype(Child, Parent);

const child = new Child('child', 10);
child.sayName(); // 'child'
console.log(child.age); // 10