Express code explainers

javascript

const ROLE_PERMISSIONS = {
  admin: ['users:read', 'users:write', 'billing:read', 'billing:write'],
  manager: ['users:read', 'billing:read'],
  member: ['users:read'],

Role-based permissions middleware in Express

authorization middleware rbac

Intermediate 9 steps

javascript

const express = require('express');
const app = express();
 
app.get('/health', (req, res) => res.json({ status: 'ok' }));

Graceful shutdown in an Express server

graceful-shutdown signal-handling connection-tracking

Advanced 9 steps

javascript

const express = require('express');
const { AsyncLocalStorage } = require('async_hooks');
const { randomUUID } = require('crypto');

Per-request logging context in Express

async-local-storage middleware structured-logging

Advanced 8 steps

javascript

const express = require('express');
const cookieParser = require('cookie-parser');
 
const router = express.Router();

Remember-me login with signed cookies in Express

authentication signed-cookies sessions

Intermediate 9 steps

javascript

const express = require('express');
const multer = require('multer');
const path = require('path');
const crypto = require('crypto');

Safe image uploads with Multer in Express

file-upload multer validation

Intermediate 7 steps

javascript

const express = require('express');
const jwt = require('jsonwebtoken');
const crypto = require('crypto');

Refresh token rotation in Express

jwt token-rotation authentication

Advanced 9 steps

javascript

const express = require('express');
const EventEmitter = require('events');
 
const router = express.Router();

Server-Sent Events with Express

server-sent-events streaming event-emitter

Advanced 8 steps

javascript

const crypto = require('crypto');
 
function inMemoryCache({ maxAge = 60_000, maxEntries = 500 } = {}) {
  const store = new Map();

Building an in-memory cache middleware in Express

caching middleware etag

Advanced 10 steps

javascript

const express = require('express');
const router = express.Router();
const { pool } = require('../db');
const redis = require('../redis');

Building a health check endpoint in Express

health-check timeouts promise-race

Intermediate 9 steps

javascript

class TokenBucket {
  constructor({ capacity, refillPerSecond }) {
    this.capacity = capacity;
    this.refillPerSecond = refillPerSecond;

How token-bucket rate limiting works in Express

rate-limiting token-bucket middleware

Intermediate 7 steps

javascript

const express = require('express');
const router = express.Router();
const db = require('../db');

Building a paginated articles endpoint in Express

pagination input-validation async-await

Intermediate 8 steps

javascript

const express = require('express');
const session = require('express-session');
const RedisStore = require('connect-redis').default;
const { createClient } = require('redis');

Redis-backed session auth in Express

sessions authentication redis

Intermediate 8 steps

javascript

const express = require('express');
const router = express.Router();
 
router.get('/articles/:slug', async (req, res, next) => {

Content negotiation with res.format in Express

content-negotiation routing error-handling

Intermediate 9 steps

javascript

const express = require('express');
const { z } = require('zod');
const router = express.Router();

Validating query params with Zod in Express

validation schema-parsing query-building

Intermediate 9 steps

javascript

const express = require('express');
const compression = require('compression');
const zlib = require('zlib');

Tuning Express response compression

compression middleware http

Intermediate 9 steps

javascript

const logger = require('./logger');
 
class AppError extends Error {
  constructor(message, statusCode = 500, details = null) {

Centralized error handling in Express

error-handling middleware custom-errors

Intermediate 8 steps

javascript

const crypto = require('crypto');
 
function securityHeaders(options = {}) {
  const {

A configurable security-headers middleware in Express

middleware http-headers content-security-policy

Intermediate 7 steps

javascript

const { validationResult, matchedData } = require('express-validator');
 
function validate(schema) {
  const runners = schema.map((rule) => rule.run.bind(rule));

A reusable validation middleware in Express

middleware validation higher-order-functions

Intermediate 8 steps