typescript

typescript
export interface CartItem {
  sku: string;
  name: string;
  unitPrice: number; // cents
  qty: number;
}

Shopping Cart Pricing with a useReducer State Machine and a Pure Discount Engine

react usereducer typescript
by codesnips 3 tabs
typescript
export interface AnalyticsEvent {
  name: string;
  props?: Record<string, unknown>;
  ts: number;
}

Batching Analytics Events With Interval Flush and Backpressure in TypeScript

analytics batching queue
by codesnips 3 tabs
typescript
import { RequestHandler } from 'express';
import { ZodTypeAny, ZodError } from 'zod';

export class ValidationError extends Error {
  status = 422;
  constructor(public issues: unknown) {

Composable Express Request Validation with Zod Schema Middleware

express validation zod
by codesnips 3 tabs
typescript
import { Injectable, Scope } from '@nestjs/common';
import { DataSource, EntityManager, QueryRunner } from 'typeorm';

@Injectable({ scope: Scope.REQUEST })
export class TransactionContext {
  private queryRunner?: QueryRunner;

Request-Scoped TypeORM QueryRunner Provider for Transactional Writes in NestJS

nestjs typeorm transactions
by codesnips 3 tabs
typescript
import { z } from "zod";

const flagValueSchema = z.union([
  z.boolean(),
  z.object({
    rollout: z.number().min(0).max(100),

Typed Feature-Flag Gate with a Zod Config Loader and useFeatureFlag Hook in React

react feature-flags typescript-hooks
by codesnips 3 tabs
typescript
export const FLAG_REGISTRY = {
  newDashboard: {
    default: false as boolean,
    description: 'Renders the redesigned dashboard shell',
  },
  maxUploadMb: {

Feature flags with a typed registry

typescript feature-flags react
by codesnips 3 tabs
typescript
import { Knex } from 'knex';

export interface RawDailyRow {
  day: string;
  order_count: string;
  gross_cents: string;

Aggregate Daily Order Totals Into a Report With Knex and a Formatter

knex postgres reporting
by codesnips 3 tabs
typescript
import { AxiosError } from 'axios';

export const RETRY_CONFIG = {
  maxRetries: 4,
  baseDelayMs: 200,
  maxDelayMs: 5_000,

Exponential-Backoff Retry Interceptor Around NestJS HttpService

nestjs http retry
by codesnips 3 tabs
typescript
import { SetMetadata } from '@nestjs/common';

export enum Role {
  User = 'user',
  Editor = 'editor',
  Admin = 'admin',

Role-Based Access Control in NestJS with a Custom Guard and @Roles Decorator

nestjs authorization rbac
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
typescript
import { z } from "zod";

export const signupSchema = z
  .object({
    email: z.string().min(1, "Email is required").email("Enter a valid email"),
    username: z

React Signup Form Validation With Zod and Field-Level Errors

react zod forms
by codesnips 3 tabs
typescript
import { Request, Response } from 'express';
import { authenticate } from './auth.service';

export async function login(req: Request, res: Response): Promise<void> {
  const { email, password } = req.body ?? {};

Password hashing with Argon2

security node argon2
by codesnips 3 tabs