JavaScript Performance · AuditJet Glossary
Code Splitting
A technique that splits JavaScript bundles into smaller chunks that are loaded on demand rather than all at once.
Code splitting reduces the initial JavaScript payload that must be parsed and executed before a page becomes interactive. In Next.js, React, and Vue, dynamic imports (import()) enable component-level code splitting. Reducing initial JS payload directly improves TBT and INP — less JavaScript executed on load means fewer long tasks.
Related terms
The total time between First Contentful Paint and Time to Interactive during which the main thread was blocked for long enough to prevent input responsiveness.
A Core Web Vital that assesses overall responsiveness by observing the latency of all qualifying interactions throughout the entire page lifecycle and reporting the worst-case value.
A dead code elimination technique used by JavaScript bundlers to remove unused exports from the final bundle.
Frequently asked questions
What is Code Splitting?
A technique that splits JavaScript bundles into smaller chunks that are loaded on demand rather than all at once.
How does AuditJet measure Code Splitting?
AuditJet runs automated Google Lighthouse audits that surface Code Splitting scores alongside actionable fix guidance. You can track Code Splitting trends across all your pages and receive alerts when the metric regresses.
Monitor Code continuously
AuditJet tracks Core Web Vitals on a schedule with revenue impact alerts — powered by Google Lighthouse and Google PageSpeed Insights.
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