How to introduce javascript code? Brief analysis of methods-Front-end Q&A-php.cn

In recent years, with the rapid development of JavaScript technology, more and more developers have begun to use this language in their projects. When using JavaScript, the introduction method is a very important part. However, in fact, there are some scenarios where it is not suitable to use the traditional introduction method of JavaScript, that is, the <script> tag. This article will walk you through these scenarios and introduce some different ways to introduce them. </p> <p>1. The traditional <script> tag</p> <p>The first-level JavaScript introduction method is to use the <script> tag in the HTML file to define and run functions by introducing external JavaScript files. . This method was first introduced by Netscape in 1995 and immediately became the preferred method for web developers. </p> <p><script src="path/to/file.js"></script>

Using this method, programmers can introduce external JavaScript files into the page, These files can be local to your computer or on the network. Just specify the file address. For example:

This will cause the browser to load Get this file from cdn.example.com and start rendering the page. This method is simple and feasible, and is especially suitable for some small projects, but it is not flexible enough and does not solve the problem of code organization well.

2. Use a modular system

As web applications become increasingly complex, the way code is organized becomes more and more complex. If you're building a large front-end project, it can be confusing to bundle all your code into a single file. Not only will it increase load times, but it can also make debugging more difficult.

At this time, modularization becomes particularly important. The goal of modularity is to break an application into small, composable parts so that each part can be developed and tested independently. Different modules can define different functions and then be combined together in different ways. These components can be JavaScript functions, classes or objects.

Now, the JavaScript community has many different ways of implementing modularity. For example, AMD (Asynchronous Module Definition) is a modular definition specification used in browsers, which loads JavaScript modules asynchronously; CommonJS is a specification used in the Node.js environment, which loads JavaScript modules synchronously; The ES6 module system is built directly into the program. It is a new JavaScript standard that appears in ES6. However, it is still not available in some older versions of browsers.

Using a modular system can effectively organize code and improve code reusability, but there are still many situations where this approach may not be suitable.

3. Use other mechanisms

Of course, there are many ways to introduce JavaScript, and some new mechanisms are constantly being developed. For example, Web Components is a browser API for creating reusable web application parts. It allows developers to package components as custom tags and supports Shadow DOM, which can improve the efficiency and reusability of applications. .

In addition, WebAssembly is also a widely used way to introduce JavaScript. WebAssembly is a low-level binary language that can be efficiently compiled into machine code on multiple platforms and run in web browsers. WebAssembly allows developers to freely use languages they are familiar with, such as C/C, Rust, etc. Using WebAssembly can improve computing performance in web applications while also providing developers with greater flexibility.

Conclusion

The choice of how to introduce JavaScript depends on the type, size, complexity and needs of your project. If you need to create a small application quickly, the traditional