Client-Side Git Hooks
Understand and implement client-side hooks like `pre-commit` and `post-merge` to enforce standards locally.
Client-Side Git Hooks is a free Git Advanced: Monorepo, Submodules & Workflows lesson on CoddyKit — lesson 1 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Git Advanced: Monorepo, Submodules & Workflows learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.
Intro to Git Hooks
Welcome! In this lesson, you'll learn about Git hooks. These are scripts that Git automatically runs before or after events like committing, merging, or pushing.
Think of them as automated assistants for your Git workflow. They help enforce project standards and automate routine tasks.
Client-Side vs. Server-Side
Git hooks come in two flavors:
- Client-side hooks: Run on your local machine. They only affect your personal repository. Examples include `pre-commit` and `post-merge`.
- Server-side hooks: Run on the Git server. They affect all pushes to the repository. We'll cover these in a later lesson.
This lesson focuses on client-side hooks and how to use them locally.
Where Hooks Live
All Git hooks are stored in the .git/hooks directory within your repository. When you initialize a new Git repository, Git populates this directory with sample hook scripts.
Let's take a look inside a typical .git/hooks folder:
ls -F .git/hooks/Activating a Hook
By default, the sample hook scripts end with .sample, making them inactive. To activate a hook, you need to:
- Remove the
.sampleextension from its filename. - Make the script executable.
Let's activate the pre-commit hook by renaming and making it executable:
cd .git/hooks
mv pre-commit.sample pre-commit
chmod +x pre-commit`pre-commit`: Your Local Guard
The pre-commit hook is one of the most useful client-side hooks. It runs just before Git asks you for a commit message and before the actual commit is created.
If the script exits with a non-zero status, Git aborts the commit. This makes it perfect for:
- Running linters (e.g., ESLint, Flake8)
- Executing unit tests
- Checking for common mistakes (e.g., debug statements)
Example: `pre-commit` for Linting
Here's a simple pre-commit script that checks if any staged files contain the word "TODO". If it finds "TODO", the commit is blocked.
You can edit the .git/hooks/pre-commit file directly to add this content:
#!/bin/sh
# Check for 'TODO' in staged changes
if git diff --cached | grep -q "TODO"; then
echo "Error: 'TODO' found in staged changes. Please resolve before committing."
exit 1
fiTesting the `pre-commit` Hook
Now, let's try to commit a file that contains "TODO". The pre-commit hook should prevent the commit.
First, create a file with "TODO", then try to commit it:
echo "This is a file with a TODO item." > my_feature.txt
git add my_feature.txt
git commit -m "Attempt to commit with TODO"`post-merge`: After the Merge
The post-merge hook runs immediately after a successful git merge or git pull (which is essentially a fetch followed by a merge or rebase).
It's useful for automating tasks that should happen after your working directory has been updated by a merge, such as:
- Installing new dependencies
- Rebuilding your project
- Updating documentation or symlinks
Example: `post-merge` for Dependencies
Imagine you're working on a project with Node.js. After merging a branch that introduced new dependencies (updated package.json), you'd want to run npm install.
Here's a post-merge script that checks if package.json was changed by the merge and runs npm install if it was:
#!/bin/sh
# Run npm install if package.json changed
if git diff --name-only HEAD@{1} HEAD | grep -q "package.json"; then
echo "package.json changed, running npm install..."
# npm install # Uncomment in a real project
echo "(npm install simulated)"
fiHook Challenge
You've learned about client-side Git hooks! Which of the following statements are TRUE about them?
Client-Side Hooks: Recap
Great job! You've successfully explored client-side Git hooks. Here's what we covered:
- What they are: Scripts that run automatically at specific Git events.
- Where they live: In the
.git/hooksdirectory. - How to activate: Rename from
.sampleand make executable. - `pre-commit`: Runs before a commit, useful for validation and linting.
- `post-merge`: Runs after a merge, good for dependency updates or rebuilding.
Client-side hooks are powerful tools for personal workflow automation and local quality checks!
Frequently asked questions
Is the “Client-Side Git Hooks” lesson free?
Yes — the full text of “Client-Side Git Hooks” is free to read here on the web, and the Git Advanced: Monorepo, Submodules & Workflows course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Git Advanced: Monorepo, Submodules & Workflows course, upgrade to CoddyKit PRO.
What will I learn in “Client-Side Git Hooks”?
Understand and implement client-side hooks like `pre-commit` and `post-merge` to enforce standards locally. You practise Git Advanced: Monorepo, Submodules & Workflows with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start Git Advanced: Monorepo, Submodules & Workflows?
No prior experience is required. Git Advanced: Monorepo, Submodules & Workflows on CoddyKit is structured for beginners through advanced learners; this is — lesson 1 of 4, so you can start here or from the beginning and move at your own pace.
How long does the “Client-Side Git Hooks” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this Git Advanced: Monorepo, Submodules & Workflows lesson?
Yes. Every Git Advanced: Monorepo, Submodules & Workflows lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.