JavaScript in Depth
JS: Filename Extension
By Xah Lee. Date:
2025-05-21
.
.js
normal JavaScript filename extension
.mjs
sometimes used for JavaScript modules.
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HTML
CSS
JS
JS Obj Ref
DOM
SVG
JS
Basics
Filename Extension
Run JavaScript
Comment
Print
Quote String
Number
Math Operators
Assignment
Boolean
Test Equality
Conditional
Loop
Array Tutorial
Object Tutorial
Value Types
Value Types
Variable
Variable
String
String Overview
Regular Expression
Property
Property Overview
Object and Inheritance
Object Overview
Array
Array Overview
Function
Function Overview
Class
Class Overview
Iterable
Iterable
for-of Loop
Spread Operator
Misc
Date
Set
Map
Import
Export
Promise
Proxy
Try Catch Throw
Style Guide
Semicolon
Strict Mode
Timing JS Code
ECMAScript News