目前我正在努力让 HMR 在我的 Webpack 2 设置中工作。我将解释我的整个设置，所以我希望这足以让某人了解正在发生的事情。
我的项目结构：
config
dev.js
prod.js
dist
css
js
index.html
node_modules
src
components
// some JavaScript components
shared
stylesheets
index.js
.babelrc
package.json
webpack.config.js
这是我的webpack.config.js文件的内容，放在我的项目的根目录中：
function buildConfig(env) {
return require('./config/' + env + '.js')(env)
}
module.exports = buildConfig;
所以在这个文件中，我可以选择将不同的环境传递给buildConfig函数。我使用此选项为开发和生产使用不同的配置文件。这是我package.json文件中的内容：
{
"main": "index.js",
"scripts": {
"build:dev": "node_modules/.bin/webpack-dev-server --env=dev",
"build:prod": "node_modules/.bin/webpack -p --env=prod"
},
},
"devDependencies": {
"autoprefixer-loader": "^3.2.0",
"babel-cli": "^6.18.0",
"babel-core": "^6.24.1",
"babel-loader": "^6.2.5",
"babel-preset-latest": "^6.16.0",
"babel-preset-react": "^6.16.0",
"babel-preset-stage-0": "^6.16.0",
"css-loader": "^0.25.0",
"extract-text-webpack-plugin": "^2.1.0",
"json-loader": "^0.5.4",
"node-sass": "^3.13.1",
"postcss-loader": "^1.3.3",
"postcss-scss": "^0.4.1",
"sass-loader": "^4.1.1",
"style-loader": "^0.13.1",
"webpack": "^2.4.1",
"webpack-dev-server": "^2.4.2"
},
"dependencies": {
"babel-plugin-react-css-modules": "^2.6.0",
"react": "^15.3.2",
"react-dom": "^15.3.2",
"react-hot-loader": "^3.0.0-beta.6",
"react-icons": "^2.2.1"
}
}
我当然有更多的领域，package.json但我不会在这里展示它们，因为它们无关紧要。
所以在开发过程中，我npm run build:dev在终端中运行命令。这将使用文件dev.js从config文件夹中。这是dev.js文件的内容：
const webpack = require('webpack');
const { resolve } = require('path');
const context = resolve(__dirname, './../src');
module.exports = function(env) {
return {
context,
entry: {
app: [
'react-hot-loader/patch',
// activate HMR for React
'webpack-dev-server/client?http://localhost:3000',
// bundle the client for webpack-dev-server
// and connect to the provided endpoint
'webpack/hot/only-dev-server',
// bundle the client for hot reloading
// only- means to only hot reload for successful updates
'./index.js'
// the entry point of our app
]
},
output: {
path: resolve(__dirname, './../dist'), // `dist` is the destination
filename: '[name].js',
publicPath: '/js'
},
devServer: {
hot: true, // enable HMR on the server
inline: true,
contentBase: resolve(__dirname, './../dist'), // `__dirname` is root of the project
publicPath: '/js',
port: 3000
},
devtool: 'inline-source-map',
module: {
rules: [
{
test: /\.js$/, // Check for all js files
exclude: /node_modules/,
use: [{
loader: 'babel-loader',
query: {
presets: ['latest', 'react'],
plugins: [
[
"react-css-modules",
{
context: __dirname + '/../src', // `__dirname` is root of project and `src` is source
"generateScopedName": "[name]__[local]___[hash:base64]",
"filetypes": {
".scss": "postcss-scss"
}
}
]
]
}
}]
},
{
test: /\.scss$/,
use: [
'style-loader',
{
loader: 'css-loader',
options: {
sourceMap: true,
modules: true,
importLoaders: 2,
localIdentName: '[name]__[local]___[hash:base64]'
}
},
'sass-loader',
{
loader: 'postcss-loader',
options: {
plugins: () => {
return [
require('autoprefixer')
];
}
}
}
]
}
]
},
plugins: [
new webpack.HotModuleReplacementPlugin(),
// enable HMR globally
new webpack.NamedModulesPlugin()
// prints more readable module names in the browser console on HMR updates
]
}
};
最后但并非最不重要的是，我的 HMR 设置。我的index.js文件中有这个设置：
import React from 'react';
import ReactDOM from 'react-dom';
import { AppContainer } from 'react-hot-loader';
import TodoApp from './components/TodoApp';
import './stylesheets/Stylesheets.scss';
const render = (Component) => {
ReactDOM.render(
<AppContainer>
<Component />
</AppContainer>,
document.querySelector('#main')
);
};
render(TodoApp);
// Hot Module Replacement API
if (module.hot) {
module.hot.accept('./components/TodoApp', () => {
render(TodoApp)
});
}
所以，当我npm start build:dev在浏览器中运行我的浏览器并转到http://localhost:3000我看到我的网站按预期工作时。这是控制台中的输出：
dev-server.js:49 [HMR] Waiting for update signal from WDS...
only-dev-server.js:66 [HMR] Waiting for update signal from WDS...
TodoApp.js:102 test
client?344c:41 [WDS] Hot Module Replacement enabled.
该test文来自于我的渲染功能TodoApp组件。这个函数看起来像这样：
render() {
console.log('test');
return(
<div styleName="TodoApp">
<TodoForm addTodo={this.addTodo} />
<TodoList todos={this.state.todos} deleteTodo={this.deleteTodo} toggleDone={this.toggleDone} updateTodo={this.updateTodo} />
</div>
);
}
所以，现在是重要的东西。我更新了这个渲染函数的返回值，这应该会触发 HMR 启动。我将渲染函数更改为这个。
render() {
console.log('test');
return(
<div styleName="TodoApp">
<p>Hi Stackoverflow</p>
<TodoForm addTodo={this.addTodo} />
<TodoList todos={this.state.todos} deleteTodo={this.deleteTodo} toggleDone={this.toggleDone} updateTodo={this.updateTodo} />
</div>
);
}
这是我在控制台中得到的输出：
client?344c:41 [WDS] App updated. Recompiling...
client?344c:41 [WDS] App hot update...
dev-server.js:45 [HMR] Checking for updates on the server...
TodoApp.js:102 test
log-apply-result.js:20 [HMR] Updated modules:
log-apply-result.js:22 [HMR] - ./components/TodoApp.js
dev-server.js:27 [HMR] App is up to date.
你会说这很好。但我的网站没有更新任何东西。
然后我将我的 HMR 代码更改为index.js：
// Hot Module Replacement API
if (module.hot) {
module.hot.accept();
}
它有效。我只是不明白。如果这是我的 HMR 代码，为什么它不起作用：
// Hot Module Replacement API
if (module.hot) {
module.hot.accept('./components/TodoApp', () => {
render(TodoApp)
});
}
顺便说一句，此设置基于https://webpack.js.org/guides/hmr-react/的设置
我希望任何人都可以帮助我。如果有人需要更多信息，请随时询问。提前致谢！
更新
忘记发我的.babelrc文件了。就是这个：
{
"presets": [
["es2015", {"modules": false}],
// webpack understands the native import syntax, and uses it for tree shaking
"react"
// Transpile React components to JavaScript
],
"plugins": [
"react-hot-loader/babel"
// EnablesReact code to work with HMR.
]
}