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This article introduces the relevant knowledge of "what is the role of classes in javascript". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

There are classes in javascript. Classes are templates for creating objects, and classes in JS are based on prototypes; javascript starts with ES6, and you can declare a class using the class keyword with the syntax "class ClassName {constructor () {...}}".

The operating environment of this tutorial: windows7 system, javascript1.8.5 version, Dell G3 computer.

There are classes in javascript.

A class is a template for creating objects. They encapsulate the data in code to process it. The classes in JS are based on prototypes, but they also have some syntax and semantics that are not similar to those shared by ES5 classes.

Class declaration

We use the class keyword to create a class whose body is in a pair of curly braces {}, and we can define the location of class members, such as methods or constructors, in curly braces {}.

Each class contains a special method constructor (), which is the constructor of the class, which is used to create and initialize an object created by class.

The syntax format for creating a class is as follows:

Class ClassName {constructor () {...}}

ES6's class keyword is really just a grammatical sugar, and it still relies on the prototype (prototype) mechanism internally.

Example:

Class phpCN {constructor (name, url) {this.name = name; this.url = url;}}

The above example creates a class called "phpCN".

Two properties are initialized in the class: "name" and "url".

Use CLA

Once the class is defined, we can use the new keyword to create the object:

Class phpCN {constructor (name, url) {this.name = name; this.url = url;}} let site = new phpCN ("," https://www.yisu.com");

The constructor method constructor () is automatically called when the object is created.

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