Webpack related errors and code explanation
Version problem
Packing style resources
Packing image resources
Packing other resources
devServer(webpack-dev-server)
Version problem
package.json file webpack and webpack-cli version is not compatible, may cause the following errors
Encountered a problem: Cannot find module'webpack-cli/bin/config-yargs'
Solution: 1. Uninstall webpack-cli => npm uninstall webpack-cli
2. Install a lower version of webpack-cli => npm install webpack-cli@3 -D
because webpack version 5.0 and above can only match webpack version 3.0 and above -cli
Packing style resources
As long as the relevant packages are downloaded at the upper level, the next level will automatically search for them.
loader download using npm i css-loader style-loader less-loader less -D
pit
(If you need to use related resources in the code, you need to download, otherwise an error will be reported, and different files must be configured with different loader configurations)
Plugins download and use (configuration) npm i html-webpack-plugin -D
function: an empty HTML will be created by default, and all the resources output will be automatically packaged.
Requirements: structured HTML files are required
// resolve用来拼接绝对路径的方法
const {
resolve } = require('path');
module.exports = {
// webpack配置
// 入口起点
entry: './src/index.js',
// 输出
output: {
// 输出文件名
filename: 'built.js',
// 输出路径
// __dirname nodejs的变量，代表当前文件的目录绝对路径
path: resolve(__dirname, 'build')
},
// loader的配置
module: {
rules: [
// 详细loader配置
// 不同文件必须配置不同loader处理
{
// 匹配哪些文件
test: /\.css$/,
// 使用哪些loader进行处理
use: [
// use数组中loader执行顺序：从右到左，从下到上 依次执行
// 创建style标签，将js中的样式资源插入进行，添加到head中生效
'style-loader',
// 将css文件变成commonjs模块加载js中，里面内容是样式字符串
'css-loader'
]
},
{
test: /\.less$/,
use: [
'style-loader',
'css-loader',
// 将less文件编译成css文件
// 需要下载 less-loader和less
'less-loader'
]
}
]
},
// plugins的配置
plugins: [
// 详细plugins的配置
],
// 模式
mode: 'development', // 开发模式
// mode: 'production'
}
Package image resources
下载 url-loader file-loader html-loader
If html-loader cannot process image images, then use html-withimg-loader (configuration needs to be changed to loader: html-withimg-loader)
const {
resolve } = require('path');
const HtmlWebpackPlugin = require('html-webpack-plugin');
module.exports = {
entry: './src/index.js',
output: {
filename: 'built.js',
path: resolve(__dirname, 'build')
},
module: {
rules: [
{
test: /\.less$/,
// 要使用多个loader处理用use
use: ['style-loader', 'css-loader', 'less-loader']
},
{
// 问题：默认处理不了html中img图片
// 处理图片资源
test: /\.(jpg|png|gif)$/,
// 使用一个loader
// 下载 url-loader file-loader
loader: 'url-loader',
options: {
// 图片大小小于8kb，就会被base64处理
// 优点: 减少请求数量（减轻服务器压力）
// 缺点：图片体积会更大（文件请求速度更慢）
limit: 8 * 1024,
// 问题：因为url-loader默认使用es6模块化解析，而html-loader引入图片是commonjs
// 解析时会出问题：[object Module]
// 解决：关闭url-loader的es6模块化，使用commonjs解析
esModule: false,
// 给图片进行重命名
// [hash:10]取图片的hash的前10位
// [ext]取文件原来扩展名
name: '[hash:10].[ext]'
}
},
{
test: /\.html$/,
// 处理html文件的img图片（负责引入img，从而能被url-loader进行处理）
loader: 'html-loader'
}
]
},
plugins: [
new HtmlWebpackPlugin({
template: './src/index.html'
})
],
mode: 'development'
};
Package other resources
const {
resolve } = require('path');
const HtmlWebpackPlugin = require('html-webpack-plugin');
module.exports = {
entry: './src/index.js',
output: {
filename: 'built.js',
path: resolve(__dirname, 'build')
},
module: {
rules: [
{
test: /\.css$/,
use: ['style-loader', 'css-loader']
},
// 打包其他资源(除了html/js/css资源以外的资源)
{
// 排除css/js/html资源
exclude: /\.(css|js|html|less)$/,
loader: 'file-loader',
options: {
name: '[hash:10].[ext]'
}
}
]
},
plugins: [
new HtmlWebpackPlugin({
template: './src/index.html'
})
],
mode: 'development'
};
DevServer
related commands:
npx webpack-dev-server
(If an error is reported, use the following one)
npx webpackserver
Then use localhost:3030 to access the
main code as follows
// 开发服务器 devServer：用来自动化（自动编译，自动打开浏览器，自动刷新浏览器~~）
// 特点：只会在内存中编译打包，不会有任何输出
// 启动devServer指令为：npx webpack-dev-server
devServer: {
// 项目构建后路径
contentBase: resolve(__dirname, 'build'),
// 启动gzip压缩
compress: true,
// 端口号
port: 3000,
// 自动打开浏览器
open: true
}