codesnips

express

typescript 
export class AppError extends Error {
  public readonly statusCode: number;
  public readonly code: string;
  public readonly isOperational: boolean;

  constructor(message: string, statusCode = 500, code = 'INTERNAL_ERROR', isOperational = true) {

Backend: normalize errors with a single Express handler

express error-handling typescript
by codesnips 4 tabs
javascript 
const crypto = require('crypto');

function computeSignature(secret, timestamp, payload) {
  return crypto
    .createHmac('sha256', secret)
    .update(`${timestamp}.${payload}`, 'utf8')

Verify Stripe-Style Webhook Signatures With HMAC in Express Before Processing

webhooks hmac security
by codesnips 2 tabs
typescript 
import { Response } from 'express';

type Client = { id: number; res: Response };

const clients = new Map<string, Set<Client>>();
let nextId = 1;

SSE endpoint for server-to-browser events

realtime sse express
by codesnips 3 tabs
lua 
-- KEYS[1] = current window key, KEYS[2] = previous window key
-- ARGV: limit, window_ms, elapsed_ms
local limit = tonumber(ARGV[1])
local window = tonumber(ARGV[2])
local elapsed = tonumber(ARGV[3])

Sliding-Window Rate Limiting for Express Routes Backed by Redis

express redis rate-limiting
by codesnips 4 tabs
typescript 
const rawOrigins = process.env.ALLOWED_ORIGINS ?? "";

export const allowedOrigins = new Set(
  rawOrigins
    .split(",")
    .map((o) => o.trim())

CORS configuration that’s explicit (no *)

security http express
by codesnips 3 tabs
javascript 
class TokenBucket {
  constructor(capacity, refillPerSecond) {
    this.capacity = capacity;
    this.refillPerMs = refillPerSecond / 1000;
    this.tokens = capacity;
    this.lastRefill = Date.now();

Token Bucket Rate Limiter Middleware for Express with Per-Key Buckets

nodejs express rate-limiting
by codesnips 4 tabs
typescript 
export type ErrorCode =
  | 'VALIDATION'
  | 'UNAUTHENTICATED'
  | 'FORBIDDEN'
  | 'NOT_FOUND'
  | 'CONFLICT'

API error shape that frontend can rely on

typescript express react
by codesnips 4 tabs
javascript 
const jwt = require('jsonwebtoken');

const SECRET = process.env.JWT_SECRET;
const ALGORITHM = 'HS256';
const ACCESS_TTL = '15m';

JWT Authentication Middleware in Express That Populates req.user

express jwt authentication
by codesnips 3 tabs
javascript 
const { z } = require('zod');

const signupSchema = z
  .object({
    email: z
      .string()

Reusable Zod Schema Validation Middleware for Express Signup Routes

express zod validation
by codesnips 3 tabs
typescript 
import { S3Client } from "@aws-sdk/client-s3";
import { createPresignedPost, PresignedPost } from "@aws-sdk/s3-presigned-post";
import { randomUUID } from "crypto";

const s3 = new S3Client({ region: process.env.AWS_REGION });
const BUCKET = process.env.UPLOAD_BUCKET!;

Pre-signed S3 upload from the browser

s3 security aws-sdk
by codesnips 3 tabs
typescript 
export interface Cursor {
  createdAt: string;
  id: string;
}

export function encodeCursor(c: Cursor): string {

Cursor Pagination for a REST List Endpoint with a Typed Fetch Client

typescript express rest
by codesnips 3 tabs
typescript 
import { createHash } from "crypto";
import { Request, Response } from "express";

export function computeEtag(body: string): string {
  const digest = createHash("sha1").update(body).digest("base64");
  return `"${digest}"`;

ETag + conditional GET for read-heavy endpoints

performance express http-caching
by codesnips 3 tabs