Contributing to Node.js Core

# Fork and clone
git clone https://github.com/YOUR_USERNAME/node.git
cd node

# Add upstream remote
git remote add upstream https://github.com/nodejs/node.git

# Build
./configure && make -j$(nproc)

# Verify
./node -v
make test

node/
├── src/                 # C++ source code
│   ├── node.cc          # Entry point
│   ├── node_*.cc        # Core modules (C++)
│   └── crypto/          # Crypto implementation
├── lib/                 # JavaScript source code
│   ├── internal/        # Internal modules
│   └── *.js             # Public API modules
├── deps/                # Dependencies
│   ├── v8/              # V8 engine
│   ├── uv/              # libuv
│   └── openssl/         # OpenSSL
├── test/                # Tests
│   ├── parallel/        # Parallel tests
│   ├── sequential/      # Sequential tests
│   └── fixtures/        # Test fixtures
├── doc/                 # Documentation
├── tools/               # Build tools
└── benchmark/           # Benchmarks

# Browse issues labeled "good first issue"
# https://github.com/nodejs/node/labels/good%20first%20issue

# Or use GitHub CLI
gh issue list --label "good first issue" --repo nodejs/node

# Update main
git checkout main
git pull upstream main

# Create feature branch
git checkout -b fix-issue-12345

subsystem: short description

Longer explanation of the change if needed.
Can span multiple paragraphs.

Fixes: https://github.com/nodejs/node/issues/12345
Refs: https://github.com/nodejs/node/pull/12344

# Bug fix
fs: fix race condition in readdir

# New feature
stream: add toArray method

# Test
test: add missing coverage for http

# Documentation
doc: clarify buffer.slice behavior

# Build
build: fix gyp warnings on Windows

# Run linters
make lint
make lint-cpp
make lint-js
make lint-md

# Auto-fix some issues
make lint-js-fix

// test/parallel/test-fs-read.js
'use strict';
const common = require('../common');
const assert = require('assert');
const fs = require('fs');

// Test description
{
  const expected = 'test content';
  const file = common.tmpDir + '/test-file.txt';

  fs.writeFileSync(file, expected);

  fs.readFile(file, 'utf8', common.mustCall((err, data) => {
    assert.ifError(err);
    assert.strictEqual(data, expected);
  }));
}

// Use common.mustCall() to ensure callbacks are called
// Use common.mustNotCall() to ensure callbacks are not called
// Use assert.throws() for expected errors

# Run all tests
make test

# Run specific test
./node test/parallel/test-fs-read.js

# Run tests matching pattern
python tools/test.py parallel/test-fs-*

# Run with specific options
./node --test-isolation=none test/parallel/test-fs-read.js

# Run benchmarks
node benchmark/fs/readfile.js

# Push to your fork
git push origin fix-issue-12345

# Create PR via GitHub CLI
gh pr create \
  --title "fs: fix race condition in readdir" \
  --body "Fixes #12345

This PR addresses the race condition in fs.readdir() by...

**Test plan:**
- Added test in test/parallel/test-fs-readdir-race.js
- Ran existing fs tests
"

├── lint (code style)
├── test-linux (Ubuntu)
├── test-macos
├── test-windows
├── test-asan (Address Sanitizer)
├── test-valgrind
└── coverage

# Make changes based on review
git add .
git commit -m "address review feedback"
git push origin fix-issue-12345

# Squash if needed
git rebase -i HEAD~3
git push --force origin fix-issue-12345

# Fetch PR
git fetch upstream pull/12345/head:pr-12345
git checkout pr-12345

# Review changes
git log upstream/main..HEAD
git diff upstream/main

# Land (after approval)
git checkout main
git pull upstream main
git merge --squash pr-12345

# Add metadata
git commit --amend
# Add: PR-URL: https://github.com/nodejs/node/pull/12345
# Add: Reviewed-By: Name <email>

# Push
git push upstream main

subsystem: description

Detailed explanation of the change.

PR-URL: https://github.com/nodejs/node/pull/12345
Fixes: https://github.com/nodejs/node/issues/12344
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

1. Consensus seeking
2. If no consensus, TSC vote
3. Lazy consensus for routine changes
4. Explicit approval for breaking changes

// Use 2-space indentation
// Use snake_case for variables and functions
// Use PascalCase for classes
// Use SCREAMING_CASE for macros

class MyClass : public BaseClass {
 public:  // 1 space before public/private
  void DoSomething();

 private:
  int my_variable_;  // Trailing underscore for members
};

// Wrap at 80 characters
// Use nullptr, not NULL
// Prefer std::unique_ptr over raw pointers

// Use Maybe<T> for operations that can fail
v8::MaybeLocal<v8::Value> result = SomeOperation();
if (result.IsEmpty()) {
  // Handle error
  return;
}
v8::Local<v8::Value> value = result.ToLocalChecked();

// Use CHECK macros for invariants
CHECK_NOT_NULL(env);
CHECK_EQ(status, 0);
CHECK_GE(length, 0);

'use strict';  // Always include

// Use const/let, never var
const x = 1;
let y = 2;

// Use arrow functions for callbacks
array.map((item) => item.value);

// Destructuring
const { a, b } = obj;

// Template literals
const message = `Value is ${value}`;

// Use primordials for built-ins in internal code
const {
  ArrayPrototypeMap,
  ObjectDefineProperty,
} = primordials;

// lib/internal/my_module.js
'use strict';

const {
  ArrayIsArray,
} = primordials;

// Internal binding
const { myBinding } = internalBinding('my_binding');

// Validators
const {
  validateString,
  validateNumber,
} = require('internal/validators');

function myFunction(arg) {
  validateString(arg, 'arg');
  // Implementation
}

module.exports = {
  myFunction,
};

# Checkout release branch
git checkout v18.x

# Cherry-pick commit
git cherry-pick -x <commit-hash>

# Update commit message
git commit --amend
# Add: Backport-PR-URL: https://github.com/nodejs/node/pull/12346