webpack5基础--14_优化css

Css 处理

提取 Css 成单独文件

Css 文件目前被打包到 js 文件中，当 js 文件加载时，会创建一个 style 标签来生成样式

这样对于网站来说，会出现闪屏现象，用户体验不好

我们应该是单独的 Css 文件，通过 link 标签加载性能才好

1. 下载包

npm i mini-css-extract-plugin -D

2. 配置

• webpack.prod.js

const path = require("path");
const ESLintWebpackPlugin = require("eslint-webpack-plugin");
const HtmlWebpackPlugin = require("html-webpack-plugin");
const MiniCssExtractPlugin = require("mini-css-extract-plugin");module.exports = {entry: "./src/main.js",output: {path: path.resolve(__dirname, "../dist"), // 生产模式需要输出filename: "static/js/main.js", // 将 js 文件输出到 static/js 目录中clean: true,},module: {rules: [{// 用来匹配 .css 结尾的文件test: /\.css$/,// use 数组里面 Loader 执行顺序是从右到左use: [MiniCssExtractPlugin.loader, "css-loader"],},{test: /\.less$/,use: [MiniCssExtractPlugin.loader, "css-loader", "less-loader"],},{test: /\.s[ac]ss$/,use: [MiniCssExtractPlugin.loader, "css-loader", "sass-loader"],},{test: /\.styl$/,use: [MiniCssExtractPlugin.loader, "css-loader", "stylus-loader"],},{test: /\.(png|jpe?g|gif|webp)$/,type: "asset",parser: {dataUrlCondition: {maxSize: 10 * 1024, // 小于10kb的图片会被base64处理},},generator: {// 将图片文件输出到 static/imgs 目录中// 将图片文件命名 [hash:8][ext][query]// [hash:8]: hash值取8位// [ext]: 使用之前的文件扩展名// [query]: 添加之前的query参数filename: "static/imgs/[hash:8][ext][query]",},},{test: /\.(ttf|woff2?)$/,type: "asset/resource",generator: {filename: "static/media/[hash:8][ext][query]",},},{test: /\.js$/,exclude: /node_modules/, // 排除node_modules代码不编译loader: "babel-loader",},],},plugins: [new ESLintWebpackPlugin({// 指定检查文件的根目录context: path.resolve(__dirname, "../src"),}),new HtmlWebpackPlugin({// 以 public/index.html 为模板创建文件// 新的html文件有两个特点：1. 内容和源文件一致 2. 自动引入打包生成的js等资源template: path.resolve(__dirname, "../public/index.html"),}),// 提取css成单独文件new MiniCssExtractPlugin({// 定义输出文件名和目录filename: "static/css/main.css",}),],// devServer: {//   host: "localhost", // 启动服务器域名//   port: "3000", // 启动服务器端口号//   open: true, // 是否自动打开浏览器// },mode: "production",
};

3. 运行指令

npm run build

Css 兼容性处理

1. 下载包

npm i postcss-loader postcss postcss-preset-env -D

2. 配置

• webpack.prod.js

const path = require("path");
const ESLintWebpackPlugin = require("eslint-webpack-plugin");
const HtmlWebpackPlugin = require("html-webpack-plugin");
const MiniCssExtractPlugin = require("mini-css-extract-plugin");module.exports = {entry: "./src/main.js",output: {path: path.resolve(__dirname, "../dist"), // 生产模式需要输出filename: "static/js/main.js", // 将 js 文件输出到 static/js 目录中clean: true,},module: {rules: [{// 用来匹配 .css 结尾的文件test: /\.css$/,// use 数组里面 Loader 执行顺序是从右到左use: [MiniCssExtractPlugin.loader,"css-loader",{loader: "postcss-loader",options: {postcssOptions: {plugins: ["postcss-preset-env", // 能解决大多数样式兼容性问题],},},},],},{test: /\.less$/,use: [MiniCssExtractPlugin.loader,"css-loader",{loader: "postcss-loader",options: {postcssOptions: {plugins: ["postcss-preset-env", // 能解决大多数样式兼容性问题],},},},"less-loader",],},{test: /\.s[ac]ss$/,use: [MiniCssExtractPlugin.loader,"css-loader",{loader: "postcss-loader",options: {postcssOptions: {plugins: ["postcss-preset-env", // 能解决大多数样式兼容性问题],},},},"sass-loader",],},{test: /\.styl$/,use: [MiniCssExtractPlugin.loader,"css-loader",{loader: "postcss-loader",options: {postcssOptions: {plugins: ["postcss-preset-env", // 能解决大多数样式兼容性问题],},},},"stylus-loader",],},{test: /\.(png|jpe?g|gif|webp)$/,type: "asset",parser: {dataUrlCondition: {maxSize: 10 * 1024, // 小于10kb的图片会被base64处理},},generator: {// 将图片文件输出到 static/imgs 目录中// 将图片文件命名 [hash:8][ext][query]// [hash:8]: hash值取8位// [ext]: 使用之前的文件扩展名// [query]: 添加之前的query参数filename: "static/imgs/[hash:8][ext][query]",},},{test: /\.(ttf|woff2?)$/,type: "asset/resource",generator: {filename: "static/media/[hash:8][ext][query]",},},{test: /\.js$/,exclude: /node_modules/, // 排除node_modules代码不编译loader: "babel-loader",},],},plugins: [new ESLintWebpackPlugin({// 指定检查文件的根目录context: path.resolve(__dirname, "../src"),}),new HtmlWebpackPlugin({// 以 public/index.html 为模板创建文件// 新的html文件有两个特点：1. 内容和源文件一致 2. 自动引入打包生成的js等资源template: path.resolve(__dirname, "../public/index.html"),}),// 提取css成单独文件new MiniCssExtractPlugin({// 定义输出文件名和目录filename: "static/css/main.css",}),],// devServer: {//   host: "localhost", // 启动服务器域名//   port: "3000", // 启动服务器端口号//   open: true, // 是否自动打开浏览器// },mode: "production",
};

3. 控制兼容性

我们可以在 package.json 文件中添加 browserslist 来控制样式的兼容性做到什么程度。

{// 其他省略"browserslist": ["ie >= 8"]
}

想要知道更多的 browserslist 配置，查看browserslist 文档

以上为了测试兼容性所以设置兼容浏览器 ie8 以上。

实际开发中我们一般不考虑旧版本浏览器了，所以我们可以这样设置：

{// 其他省略"browserslist": ["last 2 version", "> 1%", "not dead"]
}

4. 合并配置

• webpack.prod.js

const path = require("path");
const ESLintWebpackPlugin = require("eslint-webpack-plugin");
const HtmlWebpackPlugin = require("html-webpack-plugin");
const MiniCssExtractPlugin = require("mini-css-extract-plugin");// 获取处理样式的Loaders
const getStyleLoaders = (preProcessor) => {return [MiniCssExtractPlugin.loader,"css-loader",{loader: "postcss-loader",options: {postcssOptions: {plugins: ["postcss-preset-env", // 能解决大多数样式兼容性问题],},},},preProcessor,].filter(Boolean);
};module.exports = {entry: "./src/main.js",output: {path: path.resolve(__dirname, "../dist"), // 生产模式需要输出filename: "static/js/main.js", // 将 js 文件输出到 static/js 目录中clean: true,},module: {rules: [{// 用来匹配 .css 结尾的文件test: /\.css$/,// use 数组里面 Loader 执行顺序是从右到左use: getStyleLoaders(),},{test: /\.less$/,use: getStyleLoaders("less-loader"),},{test: /\.s[ac]ss$/,use: getStyleLoaders("sass-loader"),},{test: /\.styl$/,use: getStyleLoaders("stylus-loader"),},{test: /\.(png|jpe?g|gif|webp)$/,type: "asset",parser: {dataUrlCondition: {maxSize: 10 * 1024, // 小于10kb的图片会被base64处理},},generator: {// 将图片文件输出到 static/imgs 目录中// 将图片文件命名 [hash:8][ext][query]// [hash:8]: hash值取8位// [ext]: 使用之前的文件扩展名// [query]: 添加之前的query参数filename: "static/imgs/[hash:8][ext][query]",},},{test: /\.(ttf|woff2?)$/,type: "asset/resource",generator: {filename: "static/media/[hash:8][ext][query]",},},{test: /\.js$/,exclude: /node_modules/, // 排除node_modules代码不编译loader: "babel-loader",},],},plugins: [new ESLintWebpackPlugin({// 指定检查文件的根目录context: path.resolve(__dirname, "../src"),}),new HtmlWebpackPlugin({// 以 public/index.html 为模板创建文件// 新的html文件有两个特点：1. 内容和源文件一致 2. 自动引入打包生成的js等资源template: path.resolve(__dirname, "../public/index.html"),}),// 提取css成单独文件new MiniCssExtractPlugin({// 定义输出文件名和目录filename: "static/css/main.css",}),],// devServer: {//   host: "localhost", // 启动服务器域名//   port: "3000", // 启动服务器端口号//   open: true, // 是否自动打开浏览器// },mode: "production",
};

5. 运行指令

npm run build

Css 压缩

1. 下载包

npm i css-minimizer-webpack-plugin -D

2. 配置

• webpack.prod.js

const path = require("path");
const ESLintWebpackPlugin = require("eslint-webpack-plugin");
const HtmlWebpackPlugin = require("html-webpack-plugin");
const MiniCssExtractPlugin = require("mini-css-extract-plugin");
const CssMinimizerPlugin = require("css-minimizer-webpack-plugin");// 获取处理样式的Loaders
const getStyleLoaders = (preProcessor) => {return [MiniCssExtractPlugin.loader,"css-loader",{loader: "postcss-loader",options: {postcssOptions: {plugins: ["postcss-preset-env", // 能解决大多数样式兼容性问题],},},},preProcessor,].filter(Boolean);
};module.exports = {entry: "./src/main.js",output: {path: path.resolve(__dirname, "../dist"), // 生产模式需要输出filename: "static/js/main.js", // 将 js 文件输出到 static/js 目录中clean: true,},module: {rules: [{// 用来匹配 .css 结尾的文件test: /\.css$/,// use 数组里面 Loader 执行顺序是从右到左use: getStyleLoaders(),},{test: /\.less$/,use: getStyleLoaders("less-loader"),},{test: /\.s[ac]ss$/,use: getStyleLoaders("sass-loader"),},{test: /\.styl$/,use: getStyleLoaders("stylus-loader"),},{test: /\.(png|jpe?g|gif|webp)$/,type: "asset",parser: {dataUrlCondition: {maxSize: 10 * 1024, // 小于10kb的图片会被base64处理},},generator: {// 将图片文件输出到 static/imgs 目录中// 将图片文件命名 [hash:8][ext][query]// [hash:8]: hash值取8位// [ext]: 使用之前的文件扩展名// [query]: 添加之前的query参数filename: "static/imgs/[hash:8][ext][query]",},},{test: /\.(ttf|woff2?)$/,type: "asset/resource",generator: {filename: "static/media/[hash:8][ext][query]",},},{test: /\.js$/,exclude: /node_modules/, // 排除node_modules代码不编译loader: "babel-loader",},],},plugins: [new ESLintWebpackPlugin({// 指定检查文件的根目录context: path.resolve(__dirname, "../src"),}),new HtmlWebpackPlugin({// 以 public/index.html 为模板创建文件// 新的html文件有两个特点：1. 内容和源文件一致 2. 自动引入打包生成的js等资源template: path.resolve(__dirname, "../public/index.html"),}),// 提取css成单独文件new MiniCssExtractPlugin({// 定义输出文件名和目录filename: "static/css/main.css",}),// css压缩new CssMinimizerPlugin(),],// devServer: {//   host: "localhost", // 启动服务器域名//   port: "3000", // 启动服务器端口号//   open: true, // 是否自动打开浏览器// },mode: "production",
};

3. 运行指令

npm run build