Steps to configure webpack from scratch.

for JS Projects

1. Initialize project with npm init -y.

2. Install webpack and webpack-cli as dev dependencies npm i webpack webpack-cli --save-dev

3. To configure webpack, create webpack.config.js file

4. Adding entry point (path to source folder index file) to config file

   module.exports = {
    entry : './src/index.js',
    
    }
   

5. Then we define rules to handle css/svg/ other asset files

   1. we install loaders as dev dependencies for each file type. e.g., css-loader style-loader for css files

   module.exports = {
   entry: "./src/index.js",
   module: {
       rules: [
       {
           test: /\.css$/i,
           use: ["style.loader", "css-loader"],
       },
       ],
   },
   };
   

   here in use, array of loaders is passed, which are executed from right to left.

6. To convert modern JS to support in older browsers we add babel-loader

    {
        test: /\.(js)$/,
        exclude: /node_modules/,
        use: "babel-loader",
    },
   

7. We specify output path where the bundled file should be present. usualy the dist folder

   const path = require('path)
   output: {
    path: path.resolve(__dirname,'dist'),
    filename: 'bundle.js'
   

}

8. `html-webpack-plugin` is create html file in dist which will have link to `bundle.js` file.
9. finally we set mode, if production it gets stricter.

After this we add scripts in package.json to build and serve for development.

"scripts": { "start": "webpack serve", "build": "NODE_END='production' webpack", },

we can configure devServer like

devServer: { port: 9090 }

#### Final `webpack.config.js` looks like below

```js
const path = require("path");
const HtmlWebpackPlugin = require("html-webpack-plugin");
module.exports = {
  entry: "./src/index.js",
  module: {
    rules: [
      {
        test: /\.css$/i,
        use: ["style.loader", "css-loader"],
      },
      {
        test: /\.(js)$/,
        exclude: /node_modules/,
        use: "babel-loader",
      },
      {
        test: /\.svg$/,
        use: "svg-inline-loader",
      },
    ],
  },
  output: {
    path: path.resolve(__dirname, "dist"),
    filename: "bundle.js",
  },
  plugins: [new HtmlWebpackPlugin({ title: "Development" })],
  mode: process.env.NODE_ENV === "production" ? "production" : "development",
  devtool: false,
  devServer: {
    port: 9090,
  },
};

To configure for React project

1. configure webpack as below

const path = require("path");
const HtmlWebpackPlugin = require("html-webpack-plugin");

module.exports = {
  output: {
    path: path.resolve(__dirname, "dist"),
    filename: "bundle.js",
  },
  plugins: [
    new HtmlWebpackPlugin({
      template: "src/index.html",
    }),
  ],
  devServer: {
    port: 3000,
  },
  module: {
    rules: [
      {
        test: /\.(js|jsx)$/,
        exclude: /node_modules/,
        use: "babel-loader",
      },
      {
        test: /\.(sa|sc|c)ss$/i,
        use: ["style-loader", "css-loader"],
      },
      {
        test: /\.(png|woff|woff2|eot|ttf|svg)$/,
        loader: "url-loader",
        options: { limit: false },
      },
    ],
  },
};

2. to work with react, we also need babel config :.babelrc

  {
 "presets": [
   "@babel/preset-env",
   [
     "@babel/preset-react",
     {
       "runtime": "automatic"
     }
   ]
 ]
 }

here runtime option is added to make it work with jsx transform.

3. start scripts as below

  "start": "webpack serve --mode development",
  "build": "webpack --mode production"