WebPack introductory tutorial detailed-JS Tutorial-php.cn

This time I will bring you a detailed introduction to the WebPack introductory tutorial. What are the precautions for getting started with WebPack? Here are practical cases, let’s take a look.

1. What is Webpack

WebPack can be regarded as a module packager: what it does is to analyze your project structure, find the JavaScript module and other extension languages that browsers cannot run directly (Scss, TypeScript, etc.), and Package it into a suitable format for use by the browser.

2. Why use WebPack

Many web pages today can actually be regarded as feature-rich applications. They have complex JavaScript code and a lot of dependency packages. In order to simplify the complexity of development, many good practices have emerged in the front-end community

a:Modularization allows us to refine complex programs into small files;

b: Similar to TypeScript, a development language based on JavaScript: it allows us to implement features that cannot be used directly in the current version of JavaScript, and can later be converted into JavaScript files so that the browser can recognize them;

c:scss, less and other CSS preprocessors

.........

These improvements have indeed greatly improved our development efficiency, but the files developed with them often require additional processing to be recognized by the browser, and manual processing is very anti-locking, which provides the opportunity for the emergence of tools like WebPack. need.

3. What are the characteristics of WebPack compared to Grunt and Gulp?

In fact, Webpack is not very comparable to the other two. Gulp/Grunt is a tool that can optimize the front-end development process, while WebPack is a modular solution. However, the advantages of Webpack allow Webpack to replace Gulp/Grunt. Grunt-like tools.

The way Grunt and Gulp work is: in a configuration file, specify the specific steps for tasks such as compilation, combination, compression, etc. of certain files. This tool can then automatically complete these tasks for you.

The way Webpack works is: treat your project as a whole, through a given main file (such as: index.js), Webpack will find all the dependency files of your project starting from this file, use loaders to process them, and finally Packaged as a JavaScript file that can be recognized by the browser.

Advantages: Modularity

In the eyes of webpack everything is a module! This is its indispensable advantage, including your JavaScript code, including CSS, fonts, images, etc., they can all be processed as modules only through appropriate loaders.

1、CSS

webpack provides two tools for handling style sheets, css-loader and style-loader, the two handle different tasks, css-loader allows you to use methods like @import and url(...) require() function, style-loader adds all calculated styles to the page. The combination of the two allows you to embed the style sheet into the JS file packaged by webpack.

Need to install separately: npm install --save-dev style-loader css-loader

2、CSS modules

JavaScript has evolved rapidly over the past few years through new language features, better tools, and better practices (such as modularization). Modules allow developers to transform complex code into small, clean units with clearly defined dependencies, and based on optimization tools, dependency management and load management can be automatically completed.

However, in the other part of the front end, CSS development is relatively slow, and most style sheets are still huge and full of global class names, which makes maintenance and modification very difficult and complicated.

Recently there is something called CSS modules The technology is intended to bring the modular thinking of JS into CSS. Through CSS modules, all class names and animation names only apply to the current module by default. Webpack has provided support for CSS modularity from the beginning. In CSS After configuring in the loader, all you need to do is pass "modules" to the required places, and then you can directly pass the CSS class name to the component code, and this is only effective for the current component, no need to Worry about the problems that may arise from having the same class name in different modules.

In this way, the same class names will not pollute each other

3. CSS pre-compilation

Preprocessors like Sass and Less are extensions to native CSS that allow you to use things like variables, nesting, mixins, To write CSS using inheritance and other features that do not exist in CSS, the CSS preprocessor can convert these special types of statements into CSS statements that the browser can recognize,

You may be familiar with it now. You can configure it using relevant loaders in webpack. The following are commonly used CSS processing loaders

a:less-loader

b:sass-loader

c:stylus-loader

There is also a CSS processing platform - PostCSS, which allows you to use CSS with more functions, such as how to use PostCSS. We use PostCSS to automatically add CSS prefixes to CSS code that adapt to different browsers.

First install postcss-loader and autoprefixer (plug-in that automatically adds prefixes)

npm install --save-dev postcss-loader autoprefixer

And set it in the webpack configuration file. You only need to create a new postcss keyword and declare the dependent plug-ins in it, as follows. Now the css you write will automatically add different prefixes based on the data in Can i use.

WebPack introductory tutorial detailed

2. webpack-pulgins

Plugins are used to extend Webpack functions. They will take effect throughout the entire build process and perform related tasks.

Loaders and Plugins are often confused, but they are actually completely different things. It can be said that loaders are used to process source files (JSX, Scss, Less...) during the packaging and building process, one at a time. Plugins are processed one at a time. It does not directly operate on a single file, it directly affects the entire build process.

Webpack has many built-in plug-ins, as well as many third-party plug-ins, which allow us to complete richer functions.

1. How to use the plug-in?

To use a plugin, we need to install it via npm, and then all we have to do is add an instance of the plugin in the plugins keyword section of the webpack configuration (plugins is an array). We added a plugin that implements the copyright statement. Such as HtmlWebpackPugin plug-in,

The function of this plug-in is to help you generate the final Html5 file based on a simple template. This file automatically references your packaged JS file. Each compilation inserts a different hash value into the file name.

//Install

npm install --save-dev html-webpack-pugin

I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other php Chinese websites related articles!