const path = require("path");
const webpack = require("webpack");
const { CleanWebpackPlugin } = require("clean-webpack-plugin"); //注意引入写法
const HtmlWebpackPlugin = require("html-webpack-plugin");

module.exports = {
  entry: {
    index: "./src/index.js",
  },
  output: {
    filename: "[name].[contenthash].js",
    path: path.resolve(__dirname, "build"),
  },
  module: {
    rules: [
      {
        test: /\.css$/,
        use: ["style-loader", "css-loader"],
      },
      {
        test: /\.scss$/,
        use: ["style-loader", "css-loader", "sass-loader"],
      },
      {
        test: /\.(png|svg|jpg|gif)$/,
        loader: "url-loader",
        options: {
          // limit: 10000,
          name: "img/[name].[hash:7].[ext]",
        },
      },
      {
        test: /\.(js|jsx)$/,
        use: "babel-loader",
        exclude: /node_modules/,
      },
    ],
  },

  plugins: [
    new CleanWebpackPlugin(),
    // HtmlWebpackPlugin插件功能：内存中生成html页面和打包页面并将打包好的js正确放入html页面中
    new HtmlWebpackPlugin({
      template: path.resolve(__dirname, "public/index.html"),
      filename: "index.html",
    }),
  ],

  resolve: {
    alias: {
      "@": path.resolve(__dirname, "src"),
    },
  },
  optimization: {
    splitChunks: {
      cacheGroups: {
        vendor: {
          test: /[\\/]node_modules[\\/](react|react-dom)[\\/]/,
          name: "vendor",
          chunks: "all",
        },
      },
    },
  },
};