What is the principle of new operator?

The principle of the new operator is to create an object instance by creating an empty object, pointing the this keyword to the new object, executing the constructor code and returning the new object. The working principle of the new operator: 1. Create an empty object. The new operator will first create an empty object, which will inherit from the prototype of the constructor; 2. Point this to the new object, and the new operator will create an empty object in the constructor. The this keyword points to this new object; 3. Execute the constructor code, the new operator will execute the code in the constructor, etc.

The operating system for this tutorial: Windows 10 system, DELL G3 computer.

When learning the JavaScript programming language, we often encounter the new operator. It is a key operator used to create objects. This article will delve into the principles of the new operator and explain how it works.

1. The basic concept of new operator

The new operator is an operator used to create object instances in JavaScript. By using the new operator, we can call a function and use it as a constructor to create a new object instance.

2. How the new operator works

1. Create an empty object: The new operator will first create an empty object, which will inherit from the prototype object of the constructor.

2. Point this to the new object: Next, the new operator will point the this keyword in the constructor to the new object.

3. Execute the constructor code: The new operator will execute the code in the constructor, so that you can add properties and methods to the new object.

4. Return the new object: Finally, the new operator will return the new object so that we can use it in the code.

3. Example description

In order to better understand the principle of the new operator, let us illustrate it through an example.

// 定义一个构造函数
function Person(name, age) {
  this.name = name;
  this.age = age;
}
// 使用new操作符创建对象实例
var person1 = new Person("John", 25);

In the above example, the new operator first creates an empty object and inherits it from the prototype object of the constructor Person. It then points this in the Person constructor to this new object. Next, the new operator executes the code in the constructor and adds the name and age properties to the new object. Finally, the new operator returns the new object so that we can assign it to the variable person1.

4. Notes

1. The this keyword in the constructor: the new operator will point the this keyword in the constructor to the new object, so that we can operate in the constructor new object.

2. Prototypal inheritance: The object instance created through the new operator will inherit from the prototype object of the constructor, which means that it can access the methods and properties defined in the prototype object.

3. Constructor return value: If there is a return value in the constructor and an object is returned, the new operator will return the object instead of the newly created object instance.

5. Summary

In this article, we analyzed the principle of new operator in detail. The new operator creates an object instance by creating an empty object, pointing the this keyword to the new object, executing the constructor code, and returning the new object. Understanding the principles of the new operator is very important for understanding object-oriented programming in JavaScript. I hope this article can help readers better understand and apply the new operator.

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