How to correctly use hot refresh and hot loading in webpack

This time I will bring you how to correctly use hot refresh and hot loading in webpack, and what are the precautions for using hot refresh and hot loading in webpack. The following is a practical case, let’s take a look. .

Discover the difference between hot refresh and hot loading from scaffolding

I believe that most vue developers start from vue-cli, and many beginners run happily I don’t dare to change the configuration of vue-cli at will while working on the vue project (after all, webpack is indeed very complicated, and vue-cli has also done a lot of work to optimize the experience for beginners).

In contrast, react does not provide a relatively robust scaffolding (at least it is not obviously found by me, I hope you can enlighten me). As far as I know, one is yeoman's generator-react-webpack, react's create-react-app, and a good react-starter-kit (hot loading, and integrates a lot of code, which is highly referenced).

When I was learning react, I discovered that the first two scaffolds of react mentioned above provide hot refresh rather than hot loading.

Simple distinction between hot loading and hot refresh:

Hot refresh: After the file is dynamically changed, the entire page is refreshed without retaining any status (such as input of content) Input form), which is equivalent to webpack pressing F5 to refresh for you

Hot loading: After the file is changed, the changed area is changed at the minimum cost. Try to retain the state before changing the file (after entering the input content, modify the code of other tags)

Although both of them improve the development experience compared with traditional development (manual F5), both The gap is still huge, especially as the project becomes more complex, we must solve this problem once and for all (leaving more time to develop bugs).

Hands-on modification

Configuring from scratch is another area, so we start making changes directly from vue-cli.

The following steps only list the key ones for inspiration reference. For details, please refer to the final github complete project

1. Delete vue-related dependencies, files, etc. ;Everything in the scr can be deleted

2. package.json depends on adding babel-loader webpack-dev-server react-hot-loader (the most important thing)

3. package.json command line setting "dev": "webpack-dev-server --inline --progress --config build/webpack.dev.conf.js"

4. webpack.base.conf Adding .jsx files needs to be processed by babel-loader, configure options:{plugins:['react-hot-loader/babel']}

5. . Add babelrc presets to react, and add plugins below: ['react-hot-loader/babel']

6. Create main.js in the src folder (the name must match the

   of the webpack configuration) Entry file consistent)

import 'core-js/fn/object/assign';
import React from 'react';
import ReactDOM from 'react-dom';
import { hot } from 'react-hot-loader';
import App from './pages/App'; // 自己写吧
import './assets/css/reset.scss';
// Render the main component into the dom
ReactDOM.render(<App/>, document.getElementById('app'));
export default hot(module)(App); // 热加载的关键

At this point, we can happily use react to experience the pleasure of hot loading~

The problem

In fact, we simply modify the main.js file in vue-cli to react-related code (don’t forget to configure babel to process jsx) and still use hot refresh.

After observing and comparing the local code, I found an attractive name:

In the webpack.dev.conf file:

new webpack.HotModuleReplacementPlugin()

Online

QueryLater I learned that this is the key to realizing hot loading. It requires the code itself to have the modularity property (which means that as long as the three major frameworks can write reusable components, they can take advantage of this property. ), so that hot loading can be achieved by plugging and unplugging code.

The jsx special effects of react cannot be handled by HotModuleReplacementPlugin and can only be refreshed honestly.

In this case, react-hot-loader is ready to come out. In accordance with the official usage method, you can continue to use hot reloading.

ps: For reference only, I am still exploring and learning many codes of react

I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related topics on the PHP Chinese website article!

Recommended reading:

How to deal with large files packaged by webpack

How to install npm in vue.js

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