# Just-in-Time Compilation

Runtime compilation of frequently executed JavaScript into optimized machine code.

## What is **Just-in-Time Compilation** in JavaScript?

**Just-in-Time Compilation** — Runtime compilation of frequently executed JavaScript into optimized machine code.

Level: Master · [More JavaScript terms at this level](https://www.ask-codey.com/glossary/subjects/javascript/master)

Updated: September 27, 2026

## In other subjects

- [Just-in-Time Compilation in Java](https://www.ask-codey.com/glossary/just-in-time-compilation)

Source: https://www.ask-codey.com/glossary/just-in-time-compilation-javascript