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How to organize large amounts of javascript code

王林

May 12, 2023 am 10:18 AM

With the development of front-end technology, JavaScript, as a basic and widely used programming language, is used by more and more websites and applications. Some more complex applications require large-scale use of JavaScript. At this time, how to effectively organize and manage a large amount of JavaScript code has become a very important issue.

Traditional organization method - script tag

The earliest way to organize JavaScript code is to use script tags. This method is very simple. Insert JavaScript code directly into the HTML file, as follows:

<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8">
    <title>JavaScript Code Organization</title>
    <script src="path/to/script1.js"></script>
    <script src="path/to/script2.js"></script>
  </head>
  <body>
    <h1 id="Hello-world">Hello, world!</h1>
  </body>
</html>

The advantage of this method is that it is simple and easy to use, and it is also very convenient for small projects. However, when the application scale increases, the increase in the amount of code will make it very difficult to manage, maintain and modify, and this will cause code duplication and reduce development efficiency.

The concept of modular JavaScript

In order to solve such problems, we need to understand the concept of modular JavaScript. Modularization is the decomposition of a large file into many small files, each of which contains only one functional unit. By organizing JavaScript code in a modular way, the code can be broken down into chunks for easy reuse and maintenance.

Currently, there are many JavaScript modular solutions, such as CommonJS, AMD, CMD, ES6 Modules, etc. You can choose the appropriate solution according to the needs of the project. This article will mainly introduce commonly used modularization solutions-CommonJS and ES6 Modules.

CommonJS

The CommonJS specification is a reference-based modular specification for module management and loading in non-browser environments (such as Node.js).

CommonJS modules use the require() function to introduce dependencies, and use module.exports to export modules:

//引入代码
var module1 = require('module1');
var module2 = require('module2');

//导出代码
module.exports = someFunction;

This usage is very simple and easy to manage modules and dependencies. However, it only works in Node.js environment and not in web front-end environment. In a web environment, other solutions need to be used.

ES6 Modules

ES6 Modules is an efficient module management method natively supported by modern browsers. It uses the import statement to introduce the required modules and the export statement to export the modules. The following is a simple usage example:

//引入代码
import { module1 } from './module1';
import { module2 } from './module2';

//导出代码
export { someFunction };

ES6 Modules uses import and export statements to manage and control dependencies between modules. This method is not only suitable for the Web environment, but is also a common modular solution at present.

How to organize code

In addition to the idea of modularity, there are several other methods that can help us better organize a large amount of JavaScript code: namespaces, classes, and functions.

Namespace

In JavaScript, namespace is used to distinguish the complete names of different functional modules and avoid name conflicts between different modules. A common usage of namespace is as follows:

var MyApp = MyApp || {};

MyApp.namespace = function (ns_string) {
    var parts = ns_string.split('.'),
        parent = MyApp,
        i;

    if (parts[0] === "MyApp") {
        parts = parts.slice(1);
    }

    for (i = 0; i < parts.length; i += 1) {
        if (typeof parent[parts[i]] === "undefined") {
            parent[parts[i]] = {};
        }
        parent = parent[parts[i]];
    }

    return parent;
};

MyApp.namespace("myModule.project");

MyApp.myModule.project.myFunction = function () {
    // some code here
};

By using namespace, you can better manage and view the structure of the code and avoid global name pollution.

Class

Using the concept of class can better abstract the logical code into an object-oriented model, which facilitates future code maintenance. The more common class models are as follows:

function Person(name, age) {
    this.name = name;
    this.age = age;
}

Person.prototype.sayName = function() {
    console.log("My name is " + this.name);
}

Person.prototype.sayAge = function() {
    console.log("I am " + this.age + " years old!")
}

var person1 = new Person("Jack", 20);
person1.sayName(); // My name is Jack
person1.sayAge();  // I am 20 years old!

Function

Function is one of the most commonly used tools for developers to organize code. Using functions can avoid code redundancy and duplication.

var module1 = (function() {
  var privateVar = "Hello, world!";

  function privateFunction() {
    console.log(privateVar);
  }

  return {
    publicFunction: function() {
      privateFunction();
    }
  };
})();

//调用函数
module1.publicFunction();

In short, when organizing a large amount of JavaScript code, we need to follow the modular idea and use different organization code tools to complete the abstraction and encapsulation of the code to achieve reusability and maintainability.

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