Understand the role of module bundlers in modern web development.
In modern JavaScript development, we often write our code in many separate files using ES6 modules. We also might use features that are not natively supported by browsers, like JSX (for React) or TypeScript. Browsers, however, don't understand this modular structure or special syntax out of the box. This is where module bundlers come in. A bundler like Webpack or Vite is a tool that takes all of your JavaScript files (and other assets like CSS and images) and combines them into one or more optimized files (bundles) that are ready to be served to the browser. During this process, the bundler builds a dependency graph, starting from an entry point and mapping out all the modules your application needs. It then packages them into a single file. Bundlers also run 'loaders' and 'plugins' that can transform the code. For example, a Babel loader can transpile modern JavaScript to older versions, and a CSS loader can allow you to import CSS files directly into your JavaScript. Modern bundlers like Vite also offer a highly optimized development server with features like Hot Module Replacement (HMR), which instantly updates your web page as you make changes to the code, providing a very fast and efficient development experience.