Installation

Install with Bun, npm, or yarn

npm install datezone

Requirements

• Node.js 18+, Deno or Bun
• Works in modern browsers and serverless environments

Usage Example

import { addDays, type TimeZone, toISOString } from "datezone";

// Save timeZone, preferably in a user setting
const timeZone: TimeZone = "Asia/Tokyo";

const now = Date.now();

// Add 5 days in the Asia/Tokyo timeZone
const result = addDays(now, 5, timeZone);

// Format the result in ISO string format in the Asia/Tokyo timeZone
// (YYYY-MM-DDTHH:mm:ss.sss+09:00)
console.log(toISOString(result, timeZone));

ESM Compatibility & Module Resolution

Datezone is a modern ESM module that may require configuration changes in older projects. If you encounter import errors, this section will help you resolve them.

• Pure ESM module with "type": "module" in package.json
• Uses the exports field instead of legacy main/types fields
• No legacy fallback - relies entirely on the modern exports field

Common Installation Issues

If you see errors like these, your project needs modern module resolution:

Cannot find module 'datezone' or its corresponding type declarations
Module not found: Can't resolve 'datezone'

Fix: Update Module Resolution

Update your tsconfig.json to use modern module resolution:

{
  "compilerOptions": {
    "moduleResolution": "bundler", // or "node16"/"nodenext"
    "module": "ESNext",
    "target": "ES2022"
  }
}

Module Resolution Comparison

For Older Projects

If you're working with a legacy codebase that cannot be upgraded:

1. Update TypeScript to version 4.7+ for "bundler" support
2. Use a modern bundler (Vite, Webpack 5+, or Bun)
3. Consider polyfill alternatives if stuck with very old tooling

Framework-Specific Notes

• Next.js: Requires version 13.1+ for proper ESM support
• Vite: Works out of the box with default configuration
• Webpack: Requires version 5+ with ESM support enabled
• Create React App: May need ejecting or switching to Vite