What is a JavaScript file?
JavaScript (JS) is a high-level, interpreted programming language that is one of the three core technologies of the World Wide Web alongside HTML and CSS. JavaScript enables interactive and dynamic content on web pages, server-side applications via Node.js, mobile apps, desktop apps, and much more. JavaScript files use the .js extension, with .mjs for ES modules, .cjs for CommonJS modules, and .jsx for React JSX syntax.
Our Online JavaScript Viewer renders your JS files with full syntax highlighting, making it easy to read, review, and inspect JavaScript code directly in your browser without any editor or IDE installation.
How to View JavaScript Files Online
Upload JavaScript File
Drag and drop your .js, .mjs, .cjs, or .jsx file into the viewer, or click to browse and select it from your device.
View with Syntax Highlighting
Your JavaScript code is instantly displayed with full syntax highlighting for keywords, strings, comments, and operators.
Copy or Inspect
Copy the code to your clipboard, inspect specific sections, or use it as a quick reference.
Frequently Asked Questions
What JavaScript file types are supported?
.js (standard JavaScript), .mjs (ES module JavaScript), .cjs (CommonJS module), and .jsx (React JSX) files are all supported.
What is the difference between .js and .mjs?
.js is the standard JavaScript file extension. .mjs explicitly marks a file as an ES module, enabling import/export syntax. Node.js uses the extension to determine the module system when "type" is not set in package.json.
What is a .jsx file?
.jsx files contain JavaScript with JSX syntax — an XML-like extension used by React to describe UI components. JSX must be transpiled by a tool like Babel or a bundler before running in a browser.
Is it secure to upload JavaScript files?
Yes. Your files are processed locally in your browser or securely on our server and deleted immediately after processing. No code is executed.
Can I edit the JavaScript file in the viewer?
The viewer is primarily for reading and inspecting code with syntax highlighting. For editing, use a code editor like VS Code.