What does the front-end new operator do?

The front-end new operator creates a new object instance. Specific steps: 1. Create an empty simple JavaScript object; 2. Point the "__proto__" attribute of the empty object to the prototype object of the constructor; 3. Point the this keyword inside the constructor to the newly created empty object; 4. , execute the code inside the constructor, and add properties and methods to the new object; 5. If the constructor returns an object, return this object, otherwise return the newly created object, etc.

# Operating system for this tutorial: Windows 10 system, Dell G3 computer.

In previous development, the new operator was used to create a new object instance. When using the new operator, it performs the following steps:

1. Creates an empty, simple JavaScript object (i.e. {}).

2. Point the __proto__ attribute of this empty object to the prototype object of the constructor.

3. Point the this keyword inside the constructor to this newly created empty object.

4. Execute the code inside the constructor to add properties and methods to this new object.

5. If the constructor returns an object, return this object; otherwise, return this newly created object.

Let’s analyze this process in detail:

Create an empty simple JavaScript object: This empty object will become the instance object to be created. This object will inherit the properties and methods on the constructor's prototype object.

Point the __proto__ attribute of this empty object to the prototype object of the constructor: the prototype object is an object that contains inheritable properties and methods. In JavaScript, every function has a prototype attribute that points to its prototype object. When we use the new operator to create an object, the __proto__ attribute of the new object points to the prototype object of the constructor.

Point the this keyword inside the constructor to this newly created empty object: Inside the constructor, by using the this keyword, we can add properties and methods to this new object. The this keyword here refers to the instance object currently being created.

Execute the code inside the constructor to add properties and methods to this new object: Inside the constructor, we can add properties and methods to this new object to initialize it to the state we want.

If the constructor returns an object, then return this object; otherwise, return the newly created object: if there is a return statement inside the constructor and return an object, then return this object; otherwise, return just New object created. This means that we can return a custom object inside the constructor, not necessarily the object pointed to by this.

When using the new operator to create an object instance, we create an empty object and point its __proto__ attribute to the prototype object of the constructor. The code inside the constructor is then executed to add properties and methods to this new object. Finally, if there is a return statement inside the constructor, the specified object is returned; otherwise, the newly created object is returned. In this way, we can use the constructor to create multiple instance objects, and they can all share the properties and methods on the constructor's prototype object.

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