# Why Code Can't Stop and Wait

JavaScript runs one line at a time on one thread, so code that stands and waits freezes the whole page; asynchronous code starts a wait, carries on, and finishes the job later.

![Cheat sheet: Why Code Can't Stop and Wait](https://fsdtrainingmedia.blob.core.windows.net/public/images/2026/10/f7c155ccff5b4f599ac58789f3804467.webp)

- Category: JavaScript
- Level: Apprentice
- Tags: Asynchronous Code, Blocking Code, JavaScript, JavaScript Runtime, Synchronous Code
- Updated: November 1, 2026

Source: https://www.ask-codey.com/cheat-sheets/javascript-async-basics-why-code-waits-cheat-sheet