Hot reloading templateParameters for HtmlWebpackPlugin

I have in my webpack.config.js:

const data = require('./src/data.json');

...

new HtmlWebpackPlugin({
    template: "src/index.hbs",
    filename: "index.html",
    templateParameters: {
        data: data
    },
}),

...

module: {
    rules: [
        {
            test:    /\.hbs$/,
            loader:  "handlebars-loader"
        }
    ],
},

devServer: {
    static:     './dist',
    hot:        true,
    liveReload: true,
    open:       false,
    watchFiles: ['src/**/*.hbs', './src/data.json'],

},

When run with npm start hot reloading works for my JS-Modules, but not if i make changes to the data.json. How can i reload the dev server when i make changes to that JSON-File?

Solution

You can try to use modern powerful html-bundler-webpack-plugin instead of html-webpack-plugin.

Use the data plugin option as a JSON or JS filename to recompile and reload pages after changes of variables in the data file without restarting Webpack.

Using the Bundler Plugin

An entry point is a template (HTML, handlebars, EJS, etc.).
All your source asset files (scripts, styles, images, etc.) can be specified directly in the HTML template.
The plugin resolves source files of assets in templates and replaces them with correct output URLs in the generated HTML.
The resolved assets will be processed via Webpack plugins/loaders and placed into the output directory.

Just one HtmlBundlerPlugin replaces the functionality of many plugins and loaders such as:

html-webpack-plugin
handlebars-webpack-plugin
handlebars-loader
mini-css-extract-plugin
style-loader
and many others

For example there is your page template ./src/index.hbs:

<!DOCTYPE html>
<html>
<head>
  <!-- `title` is the vaiable passed from data.json via webpack -->
  <title>{{ title }}</title>
  
  <!-- relative path to favicon source file -->
  <link href="./favicon.ico" rel="icon" />
  
  <!-- relative path to SCSS source file -->
  <link href="./style.scss" rel="stylesheet" />
  
  <!-- relative path to JS source file -->
  <script src="./main.js" defer="defer"></script>
</head>
<body>
  <h1>Hello World!</h1>
  
  <!-- relative path to image source file -->
  <img src="./images/picture.png" />
</body>
</html>

The data file can be a JSON or JS file, e.g. src/data.json

{
  "title":  "My Title"
}

The Webpack config example:

const path = require('path');
const HtmlBundlerPlugin = require('html-bundler-webpack-plugin');

module.exports = {
  plugins: [
    new HtmlBundlerPlugin({
      entry: [
        {
          import: 'src/index.hbs',
          filename: 'index.html',
          data: 'src/data.json', // <= relative path to data used in this page
        },
        // add your pages here
      ],
      data: 'src/data.json', // <= relative path to global data passed into all pages
      preprocessor: 'handlebars', // <= enable support *.hbs templates
      preprocessorOptions: {
        partials: [
           'src/partials/', // path to your partials
        ],
      },
    }),
  ],
  
  module: {
    rules: [
      {
        test: /\.(css|sass|scss)$/,
        use: ['css-loader', 'sass-loader'],
      },
      {
        test: /\.(ico|png|jp?g|webp|svg)$/,
        type: 'asset/resource',
        generator: {
          filename: 'img/[name].[hash:8][ext][query]',
        },
      },
    ],
  },
  
  // enable live reload
  devServer: {
    static: path.join(__dirname, 'dist'),
    watchFiles: {
      paths: ['src/**/*.*'],
      options: {
        usePolling: true,
      },
    },
  },
};

Here is the handlebars example used JSON data files as external data passed into templates.

P.S. You can create a small repository on GitHub and then I can help you do your project working.