JavaScript in Depth
JS: Filename Extension
By Xah Lee. Date:
2025-05-21
. Last updated:
2025-11-18
.
.js
normal JavaScript filename extension
.mjs
sometimes used for JavaScript modules.
JS: Module
Webdev Search 🔍
JavaScript in Depth
Basics
Filename Extension
Run JavaScript
Comment
Print
Quote String
Number
Math Operators
Assignment
Boolean
Test Equality
Conditional
Loop
Array basics
Object basics
Advanced
Value Types
Variable
String
Regex
Property
Object
Array
Function
Class
Iterable
Misc
Module
Try Catch Throw
ECMAScript News
Misc index
Misc. Index
Obj Ref
JS Object Reference