JavaScript (.js) Test File
text/javascript
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Two module-system fixtures so you can test both modern and legacy code paths with the same download set.
What is JavaScript?
JavaScript (.js) files contain source code written in the JavaScript programming language, the language of the web. JavaScript files are plain text files that can contain variable declarations, functions, classes, imports/exports (ES modules), and asynchronous code using Promises or async/await. JavaScript is a dynamically typed, multi-paradigm language supporting object-oriented, functional, and event-driven programming. It runs in web browsers (client-side) and on servers via Node.js (server-side). JavaScript files may use CommonJS (require/module.exports) or ES Modules (import/export) syntax. The language is essential for web development, powering interactive websites, web applications, and increasingly, mobile and desktop applications.
Why Do Developers Need Test JavaScript Files?
Developers need test JavaScript files to verify code processing tools, test syntax highlighting and linting implementations, validate module bundlers, and ensure applications correctly parse and analyze JavaScript source code.
Common Use Cases
- Code parser testing
- Module bundler validation
- Syntax highlighting testing
- Linting tool testing
- Code transformation testing
ES Modules vs CommonJS
| Aspect | ES Module (sample-module.js) | CommonJS (sample-commonjs.js) |
|---|---|---|
| Syntax | import / export | require() / module.exports |
| Environment | Browsers, Node 12+, bundlers | Node.js classic, legacy tooling |
| Loading | Static, async, tree-shakeable | Synchronous, dynamic |
| Test with | Vite, Rollup, esbuild, Node --input-type=module | Node require(), Jest defaults |
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Frequently Asked Questions
- Is this sample JavaScript file safe to use?
- Yes. All files on SampleFiles are generated programmatically with safe, blank, or sample content. They contain no executable code, macros, or malicious payloads.
- What is the file size?
- Most default sample files are small (under 10KB). Binary test files (.bin) are 1MB, and fonts and media files vary. Use our Custom Generator to create files in specific sizes up to 100MB.
- Can I use these files commercially?
- Yes. All test files are free to use for any purpose, including commercial development and testing.
- How do I test a JavaScript file?
- Run it with Node.js (node sample.js), lint it with ESLint, or bundle it with esbuild/Rollup to verify it parses. For unit tests, import the module in Jest/Vitest and assert on its exports — sample-module.js and sample-commonjs.js both export named values you can assert against.
- What is the difference between .js and .mjs?
- .mjs always uses ES module syntax, .cjs always CommonJS, while .js depends on the nearest package.json "type" field. Test all three if your tooling resolves modules — the files above cover both syntaxes.