---

title: GitHub Copilot date: 2024-12-01 10:00:00 background: bg-[#000000] tags: - AI - GitHub - Coding - Autocomplete categories: - AI intro: GitHub Copilot cheat sheet with shortcuts, usage tips, Chat features and best practices plugins: - copyCode

Overview

What is GitHub Copilot

• AI coding assistant by GitHub and OpenAI
• Trained on public code repositories
• Supports multiple IDEs and languages
• Provides code completion, generation, explanation

Supported IDEs

Supported Languages

• JavaScript/TypeScript
• Python
• Java
• C/C++/C#
• Go
• Ruby
• PHP
• And many more...

VS Code Shortcuts

Code Completion {.row-span-2}

Copilot Chat

Code Actions

JetBrains Shortcuts

Code Completion

Chat

Completion Techniques

Comment-Driven Development {.cols-2}

Function Description

# Calculate the factorial of a number recursively
# Handle edge cases for negative numbers
def factorial(n):
    # Copilot completes the implementation

Detailed Specification

// Send POST request to specified URL
// Parameters: url - request URL, data - request body
// Returns: Promise<Response>
// Throws: NetworkError if request fails
async function postData(url, data) {

Algorithm Description

# Implement binary search on sorted array
# Return index if found, -1 otherwise
# Time complexity: O(log n)
def binary_search(arr, target):

Data Transformation

// Convert array of objects to lookup map
// Input: [{id: 1, name: 'a'}, {id: 2, name: 'b'}]
// Output: {1: {id: 1, name: 'a'}, 2: {id: 2, name: 'b'}}
function arrayToMap(arr, key) {

Function Signature Guidance

Clear Naming

function calculateTotalPriceWithTax(
    items: CartItem[],
    taxRate: number
): number {

Type Annotations

def send_email(
    to: str,
    subject: str,
    body: str,
    attachments: list[str] | None = None
) -> bool:

Descriptive Parameters

function filterUsersByAge(
    users,          // Array of user objects
    minAge,         // Minimum age (inclusive)
    maxAge          // Maximum age (inclusive)
) {

Context Hints

Related Imports

import { useState, useEffect } from 'react';
import axios from 'axios';

// Copilot understands you're writing React + API
function UserList() {

Adjacent Code

users = fetch_users()
emails = [u.email for u in users]

# Copilot uses context for better completion
active_users = users.filter(

Existing Patterns

// Following existing code pattern
const getUser = (id: string) => api.get(`/users/${id}`);
const getPosts = (id: string) => api.get(`/posts/${id}`);

// Copilot follows the pattern
const getComments =

Copilot Chat

Opening Chat

VS Code:

Ctrl + Shift + I  or
Click Copilot icon in sidebar

Slash Commands {.row-span-2}

Explain Code

/explain
Select code and use this command

Fix Issues

/fix
Automatically identify and fix problems

Generate Tests

/tests
Generate tests for selected code

Generate Docs

/doc
Generate documentation comments

Optimize

@workspace /optimize
Optimize selected code

Simplify

/simplify
Simplify complex code

New File

/new
Create a new file with specified content

@ Context References

Workspace

@workspace explain the project structure

Terminal

@terminal the last command failed, how do I fix it?

VS Code

@vscode how do I configure auto-format on save?

File

@file:src/index.ts explain this file

Inline Chat

1. Select code
2. Press Ctrl + I
3. Type instruction
4. Review and accept changes

Common Instructions:

add error handling

convert to async/await

add type annotations

make this more readable

Code Generation

From Comments {.cols-2}

JavaScript Function

// Validate email format
// Return true if valid, false otherwise
function validateEmail(email) {
	// Copilot generates regex validation
}

Python Class

# User class with the following properties:
# - id: user ID (int)
# - name: username (str)
# - email: email address (str)
# - created_at: creation timestamp
# Methods: to_dict(), from_dict()
class User:

React Component

// UserCard component
// Props: user object with name, avatar, bio
// Display user info in a card layout
// Include edit button if isEditable is true
function UserCard({ user, isEditable }) {

API Endpoint

# FastAPI endpoint for user registration
# Accept: email, password, name
# Validate: email format, password strength
# Return: user object with JWT token
@app.post("/register")
async def register(

From Function Names

function sortByDateDescending(items: Item[]): Item[] {

function filterActiveSubscribers(users: User[]): User[] {

function calculateMonthlyRevenue(orders: Order[]): number {

function groupByCategory<T>(items: T[], key: keyof T): Record<string, T[]> {

Test Generation

Jest Tests

// test for validateEmail function
describe('validateEmail', () => {
	// Copilot generates test cases:
	// - valid email
	// - invalid format
	// - empty string
	// - edge cases
});

Pytest

# pytest tests for User class
class TestUser:
    # Copilot generates test methods:
    # - test_create_user
    # - test_to_dict
    # - test_from_dict
    # - test_invalid_email

Documentation

JSDoc

/**
 * [Cursor here, Copilot completes]
 */
function processOrder(order, options) {

Python Docstring

def calculate_discount(price, percentage, max_discount=None):
    """
    [Copilot completes docstring with:
    - Description
    - Args
    - Returns
    - Raises
    - Examples]
    """

TypeScript Interface

/**
 * [Copilot generates interface documentation]
 */
interface PaymentRequest {
	amount: number;
	currency: string;
	customerId: string;
}

Prompt Examples

Code Review

/explain
Review this code for:
- Potential bugs
- Performance issues
- Security vulnerabilities
- Best practice violations

Refactoring

Select code → Ctrl + I → Type:
"refactor to use async/await instead of promises"

"extract repeated logic into a helper function"

"convert to functional programming style"

Learning New APIs

/explain
How does this library's authentication work?
Show me usage examples.

Error Fixing

@terminal
I got this error:
ModuleNotFoundError: No module named 'requests'

How do I fix it?

Performance Optimization

/optimize
This function is slow with large datasets.
How can I improve its performance?

Security Review

@workspace
Review this authentication code for security issues.
Focus on:
- SQL injection
- XSS vulnerabilities
- Secure password handling

Configuration

VS Code Settings

Enable/Disable

{
	"github.copilot.enable": {
		"*": true,
		"markdown": false,
		"plaintext": false
	}
}

Inline Suggestions

{
	"github.copilot.inlineSuggest.enable": true
}

Project Instructions

Create .github/copilot-instructions.md:

# Copilot Instructions

## Code Style

-   Use TypeScript for all files
-   Follow ESLint rules
-   Use functional programming style
-   Prefer immutable data structures

## Naming Conventions

-   Variables: camelCase
-   Constants: UPPER_SNAKE_CASE
-   Classes: PascalCase
-   Files: kebab-case

## Testing Requirements

-   Use Jest framework
-   Cover edge cases
-   Include error handling tests
-   Aim for 80% coverage

## Documentation

-   JSDoc for public functions
-   Inline comments for complex logic
-   README for each module

Best Practices

Improving Suggestions

1. Write clear comments

   • Describe function purpose
   • Specify parameters and returns
   • Provide usage examples

2. Use meaningful names

   • Functions describe behavior
   • Variables express meaning
   • Complete type annotations

3. Maintain relevant context

   • Import related libraries
   • Define related types
   • Provide example data

Code Review Prompts

Select code → Ctrl + I →
"review for potential issues and suggest improvements"

Learning New Codebase

@workspace
I'm new here. Explain:
- Project structure
- Key patterns used
- How to add a new feature

CLI Tool

Installation

gh extension install github/gh-copilot

Common Commands

Explain Command

gh copilot explain "git rebase -i HEAD~3"

Suggest Command

gh copilot suggest "find files larger than 100MB"

Aliases

# Add to .bashrc or .zshrc
alias '??'='gh copilot suggest -t shell'
alias 'git?'='gh copilot suggest -t git'
alias 'gh?'='gh copilot suggest -t gh'

Example Usage

# Get shell command suggestions
?? "compress all images in current directory"

# Get git command help
git? "undo last commit but keep changes"

# Get GitHub CLI help
gh? "list my open pull requests"

Troubleshooting

Inaccurate Suggestions

• Add more context
• Write detailed comments
• Use Alt + ] to cycle suggestions
• Try rephrasing your comment

Slow Suggestions

• Check network connection
• Reduce number of open files
• Restart IDE

No Suggestions

• Confirm Copilot is enabled
• Check file type is supported
• Check status bar Copilot icon

Privacy Considerations

• Disable Copilot for sensitive code
• Check organization policies
• Use .gitignore to exclude sensitive files