webpack4.29.x成神之路（二十一） 编写一个plugin

目录

上节： 编写一个loader

目录：

插件会运行在webpack的各个生命周期，我们设计一个插件时，必须确定这个插件的执行时机。
webpack的生命周期很多，参考：https://webpack.js.org/api/co...

现在写个简单的插件，需求是在打包完成后，额外输出一个叫copyRight.txt的文件
根目录下新建plugins/copy-right.plugin.js:

module.exports = class CopyRightPlugin {
  constructor(params) {
    this.name = (params && params.name) || 'Madao';
  }
  apply(compiler) {
    /*
      compiler.hooks：webpack生命周期
    */

    const that = this;

    // 资源输出到 output 目录前执行, 是个异步钩子
    compiler.hooks.emit.tapAsync('CopyRightPlugin', (compilation, cb) => {
      // compilation.assets  打包后的内容
      // debugger;
      compilation.assets['copyRight.txt'] = {
        source() {
          // 返回文件内容
          return 'copyright by ' + that.name
        },
        size() {
          // 文件大小
          return 30
        }
      }
      cb();
    });
  }
}

es6的类就不多说了，然后再配置中引用。
webpack/webpack.prod.js:

const CleanWebpackPlugin = require('clean-webpack-plugin');
const merge = require('webpack-merge');
const baseConfig = require('./webpack.base');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
const CopyRightPlugin = require('../plugins/copy-right.plugin');

module.exports = merge(baseConfig, {
  mode: 'production',
  output: {
    filename: '[name].[contenthash:10].js'
  },
  devtool: 'cheap-module-source-map',
  module: {
    rules: [{
      test: /\.less$/,
      use: [{
        loader: MiniCssExtractPlugin.loader,
      }, 'css-loader', 'postcss-loader', 'less-loader']
    }]
  },
  plugins: [
    new CopyRightPlugin(),
    new MiniCssExtractPlugin({
      filename: '[name].css',
      chunkFilename: '[id].css'
    }),
    new CleanWebpackPlugin()
  ],
  optimization: {
    splitChunks: {
      chunks: 'all'
    }
  }
});

然后npm run build, 查看输出目录：

下节：手动配置vue-cli上