GitHub Copilot

AI pair programmer for code suggestions and chat assistance.

When to Use

• Writing new code
• Understanding existing code
• Generating tests
• Refactoring and debugging

Quick Start

# VS Code Commands
Ctrl/Cmd + I           - Open Copilot Chat
Tab                    - Accept suggestion
Esc                    - Dismiss suggestion
Alt + ]                - Next suggestion
Alt + [                - Previous suggestion

Core Concepts

Inline Suggestions

// Write a comment describing what you want
// Function to validate email address
function validateEmail(email: string): boolean {
  // Copilot suggests:
  const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
  return emailRegex.test(email);
}

// Type function signature, Copilot completes
async function fetchUserById(id: string): Promise<User> {
  // Copilot suggests implementation
}

Chat Commands

# In Copilot Chat

/explain - Explain selected code
/fix - Suggest fixes for problems
/tests - Generate unit tests
/doc - Add documentation
/new - Create new code

Common Patterns

Effective Prompting

// BE SPECIFIC
// ❌ Bad: Create a function
// ✅ Good: Create an async function that fetches user data from /api/users/:id
//          and returns a User object or null if not found

// PROVIDE CONTEXT
// Helper function for the UserService class
// Uses the existing httpClient and handles 404 gracefully
async function fetchUser(id: string): Promise<User | null> {
  // Copilot has better context now
}

// USE EXAMPLES
// Format: parseDate("2024-01-15") => Date
// Format: parseDate("invalid") => null
function parseDate(input: string): Date | null {
  // Copilot understands the pattern
}

Chat Interactions

# Explain code
@workspace explain the authentication flow

# Generate tests
@workspace /tests for UserService

# Fix issues
/fix this function throws an error when input is null

# Create documentation
/doc add JSDoc comments to this class

Best Practices

Do:

• Write clear comments describing intent
• Review all suggestions carefully
• Use chat for complex explanations
• Provide context in file headers

Don't:

• Accept without reviewing
• Trust for security-critical code
• Skip testing generated code
• Rely on it for architecture decisions

Troubleshooting

Issue	Cause	Solution
No suggestions	Extension issue	Restart VS Code
Wrong language	File not detected	Check file extension
Slow response	Network/load	Check connection

References

• GitHub Copilot Docs
• VS Code Copilot