Paste two versions of JavaScript code, or drop .js, .jsx, .mjs and .cjs files, to see every change highlighted. Use it to review a change before committing, compare a minified build with its source after formatting, or check what a dependency update changed. Diffspot highlights JavaScript syntax, marks changed words inside each line and recognizes moved blocks. Press Try an example to see it on a real JavaScript change.
How to compare JavaScript files
- Paste or drop the original JavaScript code on the left.
- Paste or drop the changed version on the right. The diff updates as you type.
- Jump between changes with F7 and Shift+F7, or switch to Unified view to read it like a pull request.
- Copy or export a unified diff, a .patch file or an HTML report.
JavaScript comparison tips
- Comparing JavaScriptComparing minified code? Run both sides through a formatter such as Prettier first, then compare with Ignore changes in whitespace on.
- Cut the noiseRenamed a variable everywhere? The word-level highlight shows each renamed identifier, so you can check that nothing else changed in those lines.
- Your code stays privateThe comparison runs on your device in WebAssembly. Proprietary code is never uploaded or stored.
- Fast on large filesFiles with hundreds of thousands of lines compare in about a second.
Frequently asked questions
Is JavaScript detected automatically?
Yes. Diffspot recognizes JavaScript from the file name (.js, .jsx, .mjs and .cjs) or from the code itself. You can also choose it in the Syntax menu.
Is my code uploaded?
No. The page loads the diff engine once; after that your code stays in the browser tab. How Diffspot works explains how you can check this yourself.
Can I get a patch file?
Yes. Export → Download .patch creates a standard unified diff that git apply or patch can apply.