The relationship between the working directory and the staging area

Basic Concepts of Working Directory and Staging Area

The Git Working Directory is the local directory of project files where developers directly edit code. The Staging Area is a unique intermediate layer in Git, used to carefully select changes to be included in the next commit. The relationship between the two is like a quality inspection process on a production line: the Working Directory produces raw materials, while the Staging Area filters qualified products.

// Example of Working Directory modification
function calculate(a, b) {
  return a + b; // Modified the algorithm logic
}

Lifecycle of File States

Files in Git go through four state changes:

1. Untracked: Newly created files
2. Modified: Changes in the Working Directory
3. Staged: Added to the Staging Area via git add
4. Committed: Finally stored in the repository

# Typical workflow for viewing state changes
git status
git add .
git commit -m "message"

The Filtering Role of the Staging Area

The Staging Area allows selective commits, such as committing only part of file modifications. This is particularly useful when fixing multiple bugs, as it enables separating solutions for different issues.

# Example of selective staging
git add src/utils/validator.js  # Only stage validation logic changes
git add tests/validator.test.js # Then stage test cases

Interactive Staging Operations

The git add -p command provides finer control, allowing you to review each change block and decide whether to stage it. For large-scale modifications, this prevents unrelated changes from being mixed into the same commit.

# Example of interactive staging
git add -p src/components/Modal.js
# Interactive options for each change block will appear

Differences in Undo Operations

Undoing changes in the Working Directory and Staging Area differs:

• Undo Working Directory changes: git checkout -- <file>
• Undo Staging Area changes: git reset HEAD <file>

// Original file content
const config = {
  apiUrl: 'https://api.example.com'
};

// After erroneous modification in the Working Directory
const config = {
  apiUrl: 'wrong URL' // Changes to be undone
};

Three-Layered Structure of Diff Comparisons

Git provides multi-level diff comparisons:

• Working Directory vs. Staging Area: git diff
• Staging Area vs. Repository: git diff --cached
• Working Directory vs. Repository: git diff HEAD

# Compare CSS modifications between Working Directory and Staging Area
git diff assets/styles/main.css

Typical Workflow in Practice

1. Complete feature development in the Working Directory
2. Use git add -p to filter relevant changes
3. Confirm staged content via git diff --cached
4. Execute git commit to generate precise commit records

# Example of a complete workflow
git add src/features/userProfile/
git diff --cached
git commit -m "Refactor user profile page component structure"

Advanced Applications of the Staging Area

The Staging Area can stage partial file modifications, which is particularly useful during large-scale refactoring. For example, when modifying both component structure and styles but wanting to commit them separately.

// Component before modification
class OldComponent extends React.Component {
  // ...
}

// Two simultaneous modifications
// 1. Changed to a functional component (structural change)
function NewComponent() {
  // 2. Added new style logic (functional enhancement)
  const [style] = useState({/*...*/});
}

Scenarios for Temporarily Saving Changes

When needing to switch branches but current work is incomplete, the git stash command saves both Working Directory and Staging Area changes simultaneously. Unlike the Staging Area, stash stores the complete uncommitted working state.

# Typical operation for urgent bug fixes
git stash push -u
git checkout hotfix-branch
# After completing the fix
git checkout feature-branch
git stash pop

Impact of Configuration on Workflow

Git configurations can alter default behaviors:

• core.autocrlf: Handles line endings
• core.ignorecase: Filename case sensitivity
  These settings affect difference detection between the Working Directory and Staging Area.

# View configurations affecting the Working Directory
git config --list | grep core

Advantages of Visualization Tools

GUI tools like GitKraken visually display differences between the Working Directory (red), Staging Area (green), and repository. For complex changes, this makes file state changes easier to understand compared to the command line.

# Generate a visual commit graph
git log --graph --oneline --all

Hook Script Intervention Points

Git hooks like pre-commit trigger before Staging Area content is committed. At this point, the Working Directory may contain unstaged changes, while the hook only checks staged files.

# Example of a pre-commit hook
#!/bin/sh
npm run lint-staged # Only checks staged files