Tree shaking and code splitting in webpack

Tree shaking and code splitting in webpack are key techniques for optimizing JavaScript bundles by removing unused code and loading modules on demand, respectively, to improve performance. Tree shaking, a form of dead code elimination, is most effective with ECMAScript modules (ESM) as opposed to CommonJS or UMD due to their static nature, allowing webpack to analyze and remove unused exports. Code splitting, on the other hand, involves dividing code into separate modules that can be loaded asynchronously, enhancing load times by only fetching necessary code when needed. Webpack automates these processes through static analysis, offering a streamlined developer experience by bundling code into chunks and handling dynamic imports, though these imports are not tree-shakable. Techniques such as namespace imports and avoiding dynamic assignments can improve tree shakability, while using the global import function facilitates code splitting by creating additional bundles for lazy-loaded modules. Despite limitations with classes, side effects, and dynamic imports, these strategies collectively contribute to achieving an optimal bundle size, thereby optimizing application performance.