1.2 KiB
1.2 KiB
title, shortTitle, type, tags, expertise, author, cover, excerpt, firstSeen
| title | shortTitle | type | tags | expertise | author | cover | excerpt | firstSeen |
|---|---|---|---|---|---|---|---|---|
| What is the difference between synchronous and asynchronous code in JavaScript? | Synchronous vs asynchronous code | question | javascript,function,promise | intermediate | chalarangelo | blog_images/pineapple-on-green.jpg | Understanding the differences between synchronous and asynchronous code is a crucial piece of knowledge for every web developer. | 2021-11-14T05:00:00-04:00 |
Synchronous code runs in sequence. This means that each operation must wait for the previous one to complete before executing.
console.log('One');
console.log('Two');
console.log('Three');
// LOGS: 'One', 'Two', 'Three'
Asynchronous code runs in parallel. This means that an operation can occur while another one is still being processed.
console.log('One');
setTimeout(() => console.log('Two'), 100);
console.log('Three');
// LOGS: 'One', 'Three', 'Two'
Asynchronous code execution is often preferable in situations where execution can be blocked indefinitely. Some examples of this are network requests, long-running calculations, file system operations etc. Using asynchronous code in the browser ensures the page remains responsive and the user experience is mostly unaffected.