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Michael's Dev Blog

Why do we need Webpack and Babel?

Webpack, Babel, Node, Javascript, Frontend2 min read

This blog post is part my knowledge management and explains why we need Webpack and Babel for modern frontend web development.

The Problem

Credit goes to Nitish Dayal: Create-React-App: A Closer Look

As single-page applications and the needs of our users have grown in complexity, so has the landscape of front-end development. Modern single-page applications can consist of multiple JS files communicating with one another in order to manipulate the DOM, reducing (and in some cases eliminating) the need to request files from a server to update an application's UI. To allow for these JavaScript files, or modules, to interact efficiently in the browser, one option is to take advantage of a module bundler. A module bundler will parse through our code, mapping out dependencies as it comes across them, to bundle our application together in a way that the browser can understand, while still allowing developers to maintain modularity and separation in the codebase.

Some React developers write their applications using ES2015+ to utilize the benefits provided by the latest JavaScript syntax. However, browser support for changes to the JavaScript language are inconsistent at best, and we want users of our applications to have the same experience regardless of their browser choice. To ensure that our applications will run consistently and smoothly across browsers, we need to transpile our code from ES2015 down to a version of JavaScript that has better support across popular browsers.


Babel is a Javascript compiler. It is mainly used to convert or transpile ECMAScript 2015+ code into a backwards compatible version of JavaScript in current and older browsers or environments.

1// Babel Input: ES2015 arrow function
2[1, 2, 3].map((n) => n + 1);
4// Babel Output: ES5 equivalent
5[1, 2, 3].map(function (n) {
6 return n + 1;


webpack is a static module bundler for modern JavaScript applications.

Simply speaking module bundlers merge multiple javascript files together into a single file, which can be easily added to the HTML code. But module bundlers can do much more...

webpack illustration

When webpack processes your application, it internally builds a dependency graph which maps every module your project needs and generates one or more bundles.

Out of the box, webpack only understands JavaScript and JSON files. Loaders allow webpack to process other types of files and convert them into valid modules that can be consumed by your application and added to the dependency graph. The babel-loader for example tells the webpack's compiler the following:

"Hey webpack compiler, when you come across a path that resolves to a '.js' file inside of a require()/import statement, use the babel-loader to transform it before you add it to the bundle."


  • Javascript language constantly evolves
  • Babel is used to transpile Javascript files
    • Developers can use the latest Javascript features
    • Babel makes sure older browsers can understand it
  • Webpack merges/bundles our Javascript files
    • Developers can organize our code in multiple files
    • Webpack bundles those files together, so that it can be easily added to the HMTL