Intro
As frontend apps become more complex and the days of simple vanilla JS stack not always an optimal nor smart move, modern build tools have become indispensable.
Build tools don’t just bundle your app’s JS into a single executable for the browser, they handle minification, transpiling, and optimization. Check out some Popular Examples.
Why?
Many libraries and frameworks have amazing features that are simply unrecognizable nor understandable by the browsers that are meant to run them, so build tools act as a layer of abstraction and middleman between them.
For example:
- React relies on JSX (JavaScript XML), which needs to be transpiled into regular JavaScript.
- Vue uses Single File Components (SFCs) that combine HTML, CSS, and JavaScript in one file.
Just like bundlers, the build tools take these features and process them into readable and executable JS for the browser.
Benefits
Module Bundling and Dependency Management
This one’s been covered in the Web Bundlers document, but basically it means to take all the different JS modules in your app and bundle them into a single (or a very few) JS file(s) for the browser to execute accordingly.
This is crucial for efficiency and speed, and handles the dependencies the different modules all need.
Cross Browser Transpilation
Different browsers do things differently, shocker! Additionally, it’s important to account for backwards compatibility and older browser versions.
Build tools transpile modern JavaScript (ES6+ or TypeScript) into older versions that older.
E.g. converting arrow functions (lambdas) into regular functions defined using function keyword.
Code Optimization
Your code’s not 100% optimized, not even if you tried real hard, not really. Build tools process it using a few techniques to get it into shape. Examples include:
- Minification: Removes unnecessary characters (e.g., whitespace, comments).
- Tree Shaking: Eliminates unused code.
- Code Splitting: Breaks your app into smaller chunks to load only what’s needed.
Hot Module Replacement (HMR)
This refers to hot reloading the app when changes are made without reloading the whole app.
Popular Examples
Vite
- Best for: Speed and simplicity.
- Why: Instant dev server startup, HMR, and optimized builds.
- Ideal for: React, Vue, and Svelte apps.
Webpack
Technically a web bundler…
- Best for: Highly configurable projects.
- Why: Mature ecosystem and extensive plugin support.
- Ideal for: Complex enterprise applications.
Parcel
- Best for: Quick setups.
- Why: Zero-config bundling with sensible defaults.
- Ideal for: Small to medium-sized projects.
Rollup
- Best for: Libraries or small packages.
- Why: Produces clean and minimal bundles.
- Ideal for: Utility libraries or reusable components.
When to avoid?
A simple project who’s needs are satisfied by regular JS module such as a simple landing space won’t benefit much from build tools.