JavaScript Bundle Optimization

Dropbox has been actively optimizing its JavaScript bundle sizes to improve web performance. This involved replacing an outdated custom module bundler with a more modern solution, Rollup. The new system implements automatic code-splitting and tree-shaking, significantly reducing the amount of JavaScript sent to the browser. This effort aims to decrease page load times and enhance the overall user experience by ensuring only necessary code is downloaded and executed. This post details the transition from a custom, manual bundler to Rollup, highlighting the benefits of automatic code-splitting and tree-shaking, and the phased rollout strategy.