React从入门到放弃之前奏(1):webpack4简介
接触webpack是好久之前的事情了,最近看了下webpack没想到都到4了。
webpack 是一个现代 JavaScript 应用程序的静态模块打包器(module bundler).
会创建1个依赖关系图(dependency graph),包含所有依赖的模块,然后将模块打包成1个或多个bundle.
webpack4 仍然支持高度可配,但完全可以不用配置文件了(基于mode)。
核心配置:
- 入口(entry):
- 输出(output):
- loader:
- 插件(plugins):
基本特性
Entry
入口起点(entry point)指示 webpack 应该使用哪个模块,来作为构建其内部依赖图的开始。
可以通过在 webpack 配置中配置 entry 属性,来指定一个入口起点(或多个入口起点)。默认值为 ./src/index.js
webpack.config.js
module.exports = { entry: { main: './src/index.js' }, };
Output
output 属性告诉 webpack 在哪里输出它所创建的 bundles,以及如何命名这些文件,默认值为./dist/[name].js
webpack.config.js
const path = require('path'); module.exports = { entry: './src/index.js', output: { path: path.resolve(__dirname, 'dist'), filename: '[name].js' } };
Loader
loader 让 webpack 能够去处理那些非 JavaScript 文件(webpack 自身只理解 JavaScript)。
loaders 有2个核心参数:
- test 属性,用于标识出需要转换的某个或某些文件。
- use 属性,表示进行转换时,应该使用哪个 loader。
const path = require('path'); const config = { output: { filename: 'bundle.js' }, module: { rules: [ { test: /\.txt$/, use: 'raw-loader' } ] } }; module.exports = config;
Plugins
插件的范围包括,从打包优化和压缩,一直到重新定义环境中的变量。插件接口功能极其强大,可以用来处理各种各样的任务。
webpack.config.js
const HtmlWebpackPlugin = require('html-webpack-plugin'); // 通过 npm 安装 const webpack = require('webpack'); // 用于访问内置插件 const config = { module: { rules: [ { test: /\.txt$/, use: 'raw-loader' } ] }, plugins: [ new webpack.optimize.UglifyJsPlugin(), new HtmlWebpackPlugin({template: './src/index.html'}) ] }; module.exports = config;
Mode
通过选择 development 或 production 之中的一个,来设置 mode 参数
webpack.config.js
module.exports = { mode: 'production' };
mode.js
// webpack.development.config.js module.exports = { + mode: 'development' - plugins: [ - new webpack.NamedModulesPlugin(), - new webpack.DefinePlugin({ "process.env.NODE_ENV": JSON.stringify("development") }), - ] }
// webpack.production.config.js module.exports = { + mode: 'production', - plugins: [ - new UglifyJsPlugin(/* ... */), - new webpack.DefinePlugin({ "process.env.NODE_ENV": JSON.stringify("production") }), - new webpack.optimize.ModuleConcatenationPlugin(), - new webpack.NoEmitOnErrorsPlugin() - ] }
常用插件
HtmlWebpackPlugin:
const HtmlWebpackPlugin = require('html-webpack-plugin'); new HtmlWebpackPlugin({ template: 'src/index.html', minify: true, hash: true })
CleanWebpackPlugin:
const CleanWebpackPlugin = require('clean-webpack-plugin'); new CleanWebpackPlugin(['dist'])
MiniCssExtractPlugin(ExtractTextPlugin):
new MiniCssExtractPlugin({ filename: "[name].css",chunkFilename: "[id].css" }) module: { rules: [{ test: /\.css$/, use: [ MiniCssExtractPlugin.loader, 'css-loader' ]} ] }
SplitChunksPlugin:
module.exports = { mode: 'development', entry: { main: './src/index.js', vendors: 'lodash' }, optimization: { splitChunks: { cacheGroups: { vendors: { test: /[\\/]node_modules[\\/]/, name: "vendors", chunks: "initial" } } } } }
配置示例
const CleanWebpackPlugin = require('clean-webpack-plugin'); const HtmlWebpackPlugin = require('html-webpack-plugin'); const MiniCssExtractPlugin = require("mini-css-extract-plugin"); const path = require('path'); module.exports = { mode: 'development', entry: { main: './src/index.js', }, devtool: 'inline-source-map', devServer: { contentBase: './dist' }, output: { path: path.resolve(__dirname, 'dist'), filename: '[name].js', }, module: { rules: [{ test: /\.css$/, use: [ MiniCssExtractPlugin.loader, 'css-loader' ] }, { test: /\.(js|jsx)$/, loader: 'babel-loader', options: { presets: ['react'] }, exclude: /node_modules/ }] }, plugins: [ new CleanWebpackPlugin(['dist']), new HtmlWebpackPlugin({ template: 'src/index.html', minify: true, hash: true }), new MiniCssExtractPlugin({ filename: "[name].css", chunkFilename: "[id].css" }) ], externals: { lodash: '_', react: 'React', 'react-dom': 'ReactDOM' }, optimization: { splitChunks: { cacheGroups: { common: { test: /[\\/]node_modules[\\/]/, name: "common", chunks: "initial" } } } } };
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