What is Code Splitting?

Code splitting is the practice of shipping smaller JavaScript files instead of one large application bundle. When a user opens the home page, code for the admin area, chart editor, or checkout step does not have to be downloaded until that screen is needed.

How Does It Work?

Modern bundlers turn dynamic imports such as import() into separate chunks. Route-level splitting gives each page its own code. Component-level splitting delays heavy parts such as date pickers, maps, rich text editors, or analytics dashboards until the user opens them.

Webpack, Vite, and similar tools can also extract shared dependencies into vendor chunks. This lets the browser reuse cached files across visits. Code splitting is often paired with lazy loading, but too many tiny chunks can increase network overhead, so the split points need to be chosen carefully.

When Is It Useful?

Admin or account screens are not needed on the first page load
Large third-party libraries are used for charts, maps, or editors
Mobile users need a faster first interaction
A single-page application’s bundle has grown too large

Business Use

In e-commerce, SaaS, and portal projects, code splitting helps users reach the first usable screen faster. A good chunk strategy is based on real traffic, popular routes, cache behavior, and performance measurements rather than bundle size alone.