Rollup

Rollup (v4) is the bundler of choice for libraries. It produces smaller, cleaner code than Webpack and pioneered Tree Shaking.

When to Use

• NPM Packages: Building a library for others to use.
• Flat Bundling: "Scope Hoisting" puts everything in one closure for performance.

Core Concepts

Tree Shaking

Rollup analyzes the import graph and excludes unused code statically.

Formats

Outputs esm, cjs, umd, iife.