Question 1

How do I read Git diff colors and symbols?

Accepted Answer

Git diff uses color-coding and symbols to show changes: Green lines with + = additions (new code added), Red lines with - = deletions (code removed), White/gray lines = unchanged context (surrounding code for reference), Blue @ symbols = hunk headers showing line numbers (@@ -10,5 +12,7 @@ means old file lines 10-15, new file lines 12-19). File indicators: --- a/file.js = old version, +++ b/file.js = new version. Understanding hunks: each colored block = one hunk (contiguous change area), white lines between hunks = unchanged code skipped for brevity. Reading strategy: scan red lines first (what was removed?), then green lines (what replaced it?), compare side-by-side to understand intent. Pro tip: if diff shows entire file changed, likely line ending issues (CRLF vs LF) or formatting changes (spaces/tabs)—use git diff --ignore-all-space to filter.

Question 2

What's the difference between git diff, git diff --staged, and git diff HEAD?

Accepted Answer

Three commands show different comparison points: git diff (no args) = compares working directory vs staging area (shows unstaged changes you haven't git added yet), useful before git add to review what you're about to stage. git diff --staged (or --cached) = compares staging area vs last commit (shows staged changes ready to commit), useful before git commit to review what will be committed. git diff HEAD = compares working directory vs last commit (shows all changes both staged and unstaged), useful for complete picture of all modifications since last commit. Workflow: 1) Make changes, 2) git diff (review before staging), 3) git add files, 4) git diff --staged (review before committing), 5) git commit. Comparing branches: git diff main..feature shows differences between branches, git diff HEAD~3 shows changes from 3 commits ago.

Question 3

How can I use Git diff for code review?

Accepted Answer

Git diff is essential for effective code reviews: Pre-review preparation: git diff main...feature-branch (three dots show changes introduced by feature, not main's progress), git diff --stat (summary showing which files changed + line counts), git diff -w (ignore whitespace to focus on logic changes). Review workflow: 1) Start with git diff --stat to identify high-risk files (500+ line changes need careful review), 2) Review critical files first (authentication, payment, security-related), 3) For each file: understand change context, check for logic errors, verify tests updated, look for code smells. Efficient reviewing: git diff --word-diff highlights word-level changes (better than line-level for small edits), git diff --color-words for even finer granularity. Red flags in diff: massive deletions without additions (functionality removed?), many files changed (scope creep?), mixing refactoring with feature adds (should be separate commits).

Question 4

Why does my Git diff show changes I didn't make?

Accepted Answer

Common causes of unexpected diffs: Line ending differences (CRLF on Windows vs LF on Mac/Linux) = entire file shows changed, fix with git config core.autocrlf true (Windows) or input (Mac/Linux). Whitespace changes (spaces vs tabs, trailing spaces) = lines identical except formatting, filter with git diff -w or --ignore-all-space. File mode changes (chmod permissions) = diff shows mode change 100644 → 100755 but no content change, disable with git config core.fileMode false. IDE auto-formatting (Prettier, ESLint fix) = formatting changes obscure real changes, commit formatting separately. Encoding changes (UTF-8 vs UTF-16) = file appears completely changed, check with file -I filename. Merged code from other branches = changes from base branch appear in your diff, use three-dot diff: git diff main...your-branch to see only your changes. Prevention: configure .gitattributes for line endings, use .editorconfig for consistent formatting, enable pre-commit hooks to catch formatting issues.

Question 5

Can I generate diffs between non-Git files or specific file versions?

Accepted Answer

Yes, Git diff works beyond Git-tracked files: Compare any two files: git diff --no-index file1.txt file2.txt (compares any files even outside Git repos), useful for comparing config files, API responses, or data files. Compare specific commit versions: git diff commit1:file.js commit2:file.js (compare same file across commits), git diff HEAD:file.js working-tree-file.js (compare committed version vs current). Compare directories: git diff --no-index dir1/ dir2/ (shows all file differences between directories). Output formats: git diff --stat (summary with file names and line counts), git diff --name-only (just file names), git diff --name-status (files + change type: A=added, M=modified, D=deleted), git diff > changes.patch (save diff to file for later application). Advanced: diff --patience for better algorithm on complex changes, diff --histogram for faster performance, diff --color-moved to track code movements. Integration: pipe git diff to tools like diff-so-fancy or delta for enhanced visual diffs with better syntax highlighting.

🔀 Git Diff Highlighter

Original Code

Modified Code

Diff View

💡 Merge Conflict Resolution Tips

📖 How to Use Git Diff Viewer

1 Paste Your Code

2 Choose View Mode

3 Review Changes

4 Resolve Conflicts

❓ Frequently Asked Questions