How to Compare JavaScript & TypeScript Files for Code Review
Code review diffs in GitHub and GitLab show raw text changes. UtraDiff adds full syntax highlighting, whitespace-aware comparison, and navigation shortcuts — making it easier to catch subtle bugs like var-to-let scope changes, broken destructuring, and async flow modifications.
Step by step
- 1
Load your source files
Drop two .js, .ts, .jsx, or .tsx files into UtraDiff. The editor activates full language support including JSX/TSX syntax highlighting, bracket matching, and folding.
- 2
Review the diff
Changes are highlighted inline with red (removed) and green (added) markers. Use Alt+Arrow (or Option+Arrow on Mac) to jump between changes — no need to scroll through unchanged code.
- 3
Toggle whitespace visibility
Enable 'Show whitespace' to see tabs, spaces, and line endings. Enable 'Ignore whitespace' to filter out Prettier/ESLint reformatting noise and focus on logic changes only.
- 4
Switch between side-by-side and inline
Side-by-side mode (default) shows both files simultaneously. Inline mode shows changes in a single column — useful for narrow screens or when the change is small and context is more important than comparison.
- 5
Share your review
Copy the diff URL to share the exact comparison with your team. The shared link preserves the file contents and diff settings.
Why UtraDiff
UtraDiff uses the same editor engine that powers VS Code, so you get identical syntax highlighting, bracket matching, and folding. The whitespace toggle is critical for JavaScript/TypeScript code review — auto-formatters change hundreds of lines cosmetically, and without filtering you cannot see the real changes. The Alt+Arrow navigation lets you skip directly between changes instead of scrolling through thousands of unchanged lines.
Tips
- For TypeScript, the diff catches type annotation changes that are invisible in runtime behaviour but critical for type safety — watch for `any` insertions.
- When reviewing a Prettier-formatted PR, enable 'Ignore whitespace' first. Then disable it once you have reviewed the logic to verify the formatting is also correct.
- JSX/TSX is fully supported — component prop changes, conditional rendering modifications, and hook dependency array updates are all syntax-highlighted.
- Compare a .js file with a .ts file to review a JavaScript-to-TypeScript migration — all added type annotations are clearly visible.
Common pitfalls
- UtraDiff compares file content, not git history. For comparing specific commits, export the file versions first (git show commit:path > file.ts).
- Minified JavaScript is supported but produces poor diffs. Run through a formatter (prettier --write) before comparing.
- Import reordering is shown as changes in text diff. This is correct behaviour — import order can affect side effects in JavaScript.