tree-shaking

Tree shaking removes dead code from JavaScript bundles by statically analyzing ES module import and export structure to drop unused exports and unreachable module code during builds. This eliminates unused exported functions so applications download and parse faster.

Yes, tree shaking requires ES2015 module syntax with named imports and exports. Bundlers rely on the static structure of ES modules to analyze dependencies and safely remove dead code, which is not possible with dynamic CommonJS require statements.

To prevent tree shaking from incorrectly removing polyfills and global styles, configure correct package.json sideEffects settings. This marks modules with side effects so the bundler retains them while still dropping truly side-effect-free unused code.

Yes, tree shaking works with both Webpack and Rollup for JavaScript bundling. Both bundlers apply dead code elimination by analyzing ES module imports, provided you use ES2015 syntax and configure package.json sideEffects correctly.

The best way to shrink a large JavaScript bundle is using tree shaking to eliminate dead exports and unreachable module code. You must apply ES module syntax with named imports and accurate package.json sideEffects configuration for safe dead code elimination.