How can I set the default timezone in nodeJs ?

Setting the default timezone in Node.js is not a straightforward operation because Node.js itself does not provide built-in functionality to set a global default timezone. Node.js typically uses the system timezone at runtime, which is the timezone set by the operating system it runs on. However, there are several methods to indirectly set or change the timezone within a Node.js application.

Method 1: Using Environment Variables

The simplest method is to set the TZ environment variable before running the Node.js application to specify the timezone. This affects all code that uses new Date() or other time-related JavaScript standard library functions.

For example, if you want to set the timezone to 'America/New_York', you can set the TZ environment variable before launching the application:

bash
export TZ='America/New_York'
node your-app.js

Or on Windows systems:

bash
set TZ=America/New_York
node your-app.js

This method is simple and easy to implement, as it impacts all created Date objects and other time-related operations.

Method 2: Using moment-timezone Library

If you need to handle multiple timezones within your application, you can use libraries like moment-timezone. This is a powerful time handling library that allows you to set and use different timezones.

First, you need to install moment-timezone:

bash
npm install moment-timezone

Then, use it in your code to create and manage time in different timezones:

javascript
const moment = require('moment-timezone');

let nowInNewYork = moment().tz('America/New_York').format();
console.log("Current time in New York: ", nowInNewYork);

let nowInTokyo = moment().tz('Asia/Tokyo').format();
console.log("Current time in Tokyo: ", nowInTokyo);

This method allows you to create date and time objects for specific timezones anywhere in your code, providing flexibility.

Method 3: Using Intl and toLocaleString

For internationalized applications, you can also utilize the Intl object and toLocaleString method to specify the timezone for formatting purposes:

javascript
const date = new Date();

const options = {
  timeZone: 'America/New_York',
  timeZoneName: 'short'
};

console.log(date.toLocaleString('en-US', options));

This method is suitable for formatting output but does not alter the timezone of internal Date objects.

Summary

Although Node.js does not directly support setting the default timezone, by setting environment variables, using third-party libraries, or leveraging internationalization APIs, we can effectively manage and manipulate different timezones. The choice of method depends on specific requirements, such as global timezone settings or handling multiple timezones.