Compare JavaScript Online
Paste two JS files below and see differences highlighted.
About JavaScript Compare Online
Compare two JavaScript files or code snippets. Find differences in JS code. Free JavaScript diff checker online. All processing happens in your browser — nothing is uploaded to any server. Completely free, no sign-up required.
JavaScript is the most widely used programming language for web development, powering everything from interactive user interfaces to server-side applications with Node.js. Our JavaScript comparison tool is essential for developers working in any JS ecosystem — whether you are writing vanilla JavaScript, building with React, Angular, Vue, or Svelte, developing Node.js backends, or maintaining TypeScript codebases. Use it to review code changes before committing, compare function implementations across branches, spot unintended modifications introduced by automated formatters or transpilers, and debug differences between development and production builds of your JavaScript bundles.
Modern JavaScript development involves complex toolchains with bundlers (Webpack, Vite, Rollup), transpilers (Babel, TypeScript compiler), and minifiers (Terser, esbuild) that transform your source code. Comparing the output of these tools across different configurations or versions is critical for debugging build issues, understanding bundle size changes, and verifying that optimizations do not alter behavior. Our diff tool handles all JavaScript syntax including ES modules (import/export), async/await patterns, destructuring, template literals, optional chaining, class syntax, generators, and any other modern ECMAScript feature. It is equally effective for comparing JSX/TSX, CommonJS modules, and even JSON configuration files used in JS projects.
Tips for effective JavaScript comparison: when comparing minified or bundled code, run it through Prettier or a similar formatter first to get readable, line-by-line diffs. For framework-specific code, compare individual component files rather than entire compiled bundles. When reviewing refactored code, pay attention to changes in function signatures, import statements, and export patterns. This tool processes everything locally in your browser — your proprietary application logic, business rules, and intellectual property remain completely private. No account required, no data stored, no limitations on usage.
Frequently Asked Questions
Can I compare minified JavaScript code?
Yes, you can paste minified JavaScript directly into the tool. However, minified code is typically on very few lines, so the diff output will show large blocks as changed rather than individual statements. For the most useful results, we strongly recommend running both code snippets through a formatter like Prettier, js-beautify, or your IDE's format command before comparing. This expands the code to one statement per line, giving you precise, granular diffs that identify exactly which functions or expressions changed.
Does this tool work with TypeScript or JSX code?
Absolutely. The tool performs text-based comparison, so it works with any JavaScript variant including TypeScript (.ts/.tsx), JSX (React), Vue single-file components, Svelte files, and even CoffeeScript or Flow-typed code. It compares the raw text regardless of syntax, making it versatile for any JS ecosystem. You can compare TypeScript source files, compiled JavaScript output, or even compare your TypeScript against the generated JavaScript to understand what the compiler produced.
How can I compare JavaScript code from different frameworks?
You can compare any two JavaScript code snippets regardless of their framework origin. This is particularly useful when migrating between frameworks (e.g., jQuery to React, AngularJS to Angular, or Vue 2 to Vue 3), comparing equivalent functionality implemented in different libraries, or reviewing how different frameworks handle the same task. Simply paste both versions and the tool will highlight all textual differences, helping you understand the structural changes involved in the migration.
Can I use this tool to review pull request changes?
Yes, this is one of the most common use cases. Copy the original file content and the modified version from your pull request, paste them into the two panels, and instantly see all changes highlighted with color coding. This is especially useful when your Git platform's diff viewer is hard to read, when you want to compare non-adjacent versions of a file, or when you need to share a diff with someone who does not have repository access.
Is my JavaScript source code kept private?
Yes, completely. All comparison processing happens entirely in your web browser using client-side JavaScript. Your code is never sent to any server, stored in any database, logged, or accessible to anyone else. This makes the tool safe for comparing proprietary application code, business logic, authentication implementations, and any other sensitive JavaScript you work with. You can verify this by monitoring your browser's Network tab during use.