What is js inheritance? js inheritance method (with code)

The content of this article is about how to create objects in js? The method of creating objects in js (with code) has certain reference value. Friends in need can refer to it. I hope it will be helpful to you.

js inheritance

js class inheritance

// 父类
var supperClass = function() {
  var id = 1;
  this.name = ['js'];
  this.superVal = function() {
    console.log('supreVal is true');
    console.log(id);
  }
}
// 父类添加共有方法
supperClass.prototype.getSupperVal = function () {
  return this.superVal();
}

// 子类
var subClass = function() {
  this.subVal = function() {
    console.log('this is subVal')
  }
}

// 继承父类
subClass.prototype = new supperClass();

// 子类添加共有方法
subClass.prototype.getsubVal = function() {
  return this.subVal();
}    

var sub = new subClass();

sub.getSupperVal();   //superValue is true
sub.getsubVal();     //this is subValue
console.log(sub.name);
sub.name.push('java');  //["javascript"]

var sub2 = new subClass();
console.log(sub2.name); //  ["js", "java"]

The core code is SubClass.prototype = new SuperClass();

Point the prototype __proto__ to the prototype object of the parent class. In this way, the subclass can access the public and protected properties and methods of the parent class. At the same time, the private properties and methods in the parent class will not be inherited by the subclass.

Disadvantages

Knock on the blackboard, as in the last paragraph of the above code, using the class inheritance method, if there is a [reference type] in the constructor of the parent class, it will It is shared by all instances in the subclass, so if an instance of a subclass changes this reference type, it will affect instances of other subclasses.

js Constructor Inheritance

var parentClass = function(name, id) {
  this.name = name;
  this.id = id;
  this.getName = function(){
    console.log(this.name)
  }
}

parentClass.prototype.show = function( ) {
  console.log(this.id)
}

var childClass = function(name, id) {
  parentClass.call(this, name, id); 
}
var subClass = new childClass('zjj', 10);

Let’s first summarize the advantages and disadvantages of class inheritance and constructor inheritance

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