{"id":17280,"library":"jstimezonedetect","title":"JavaScript Time Zone Detect","description":"jstimezonedetect is a JavaScript library designed to determine the IANA time zone key (also known as the Olson time zone database) of the user's device. As of version 1.0.7, released in 2018, the project appears to be in maintenance mode with infrequent updates, and no active development is indicated for new time zone rule changes. Its primary utility lies in obtaining a standardized time zone identifier for server-side date and time normalization without requiring user interaction. A key differentiator is its specific scope: it focuses exclusively on *modern* time zones, typically from 2010 onwards, and intentionally disregards historical time zone data or geographical location-based detection. This targeted approach means it will not differentiate between time zones that share identical modern rules (e.g., Europe/Berlin and Europe/Stockholm if their current rules align) nor provide granular historical offsets.","status":"maintenance","version":"1.0.7","language":"javascript","source_language":"en","source_url":"https://github.com/pellepim/jstimezonedetect","tags":["javascript","time","timezone","tz","date"],"install":[{"cmd":"npm install jstimezonedetect","lang":"bash","label":"npm"},{"cmd":"yarn add jstimezonedetect","lang":"bash","label":"yarn"},{"cmd":"pnpm add jstimezonedetect","lang":"bash","label":"pnpm"}],"dependencies":[],"imports":[{"note":"Primarily a CommonJS module for Node.js environments. For ESM, direct import might require a compatibility layer or bundler configuration.","wrong":"import jstz from 'jstimezonedetect';","symbol":"jstz","correct":"const jstz = require('jstimezonedetect');"},{"note":"For web environments, the library exposes the 'jstz' object directly onto the global scope after the script is loaded.","symbol":"jstz (browser global)","correct":"// Include <script src=\"path/to/dist/jstz.min.js\"></script>\n// 'jstz' object is then available globally"}],"quickstart":{"code":"const jstz = require('jstimezonedetect');\n\ntry {\n  const tz = jstz.determine();\n  console.log('Detected IANA Time Zone:', tz.name());\n} catch (error) {\n  console.error('Error detecting time zone:', error.message);\n}\n","lang":"javascript","description":"Demonstrates how to use jstimezonedetect in a Node.js environment to detect and log the client's IANA time zone name."},"warnings":[{"fix":"If historical time zone data is required, consider a more comprehensive library like `moment-timezone` or `luxon`.","message":"jstimezonedetect explicitly focuses on modern time zones (from 2010 onwards) and does not provide historical time zone data. It will not detect differences in UTC offsets for dates prior to 2010.","severity":"gotcha","affected_versions":">=1.0.0"},{"fix":"For geo-location based time zone detection, you would need to integrate with a separate geo-location service or library that provides time zone information based on coordinates.","message":"This library does not perform geo-location. It determines the time zone based on the device's system settings, not its physical location. As such, it won't differentiate between zones with identical modern rules but different geographical names (e.g., 'Europe/Berlin' vs 'Europe/Stockholm').","severity":"gotcha","affected_versions":">=1.0.0"},{"fix":"For applications requiring up-to-date time zone rules, consider libraries that are actively maintained and frequently update their time zone data, such as `luxon` or `date-fns-tz`.","message":"The project appears to be in maintenance mode, with its last release in 2018. This means it may not receive updates for changes in IANA time zone rules, potentially leading to outdated or incorrect time zone detections in regions with recent rule adjustments.","severity":"gotcha","affected_versions":">=1.0.0"},{"fix":"Test thoroughly across target environments. If inconsistencies are critical, consider explicit user input or a server-side detection fallback.","message":"The library might not provide a consistent IANA time zone name across all browsers or operating systems, as it relies on internal browser/OS heuristics to determine the zone. While it aims for IANA keys, the underlying mechanism can vary.","severity":"gotcha","affected_versions":">=1.0.0"}],"env_vars":null,"last_verified":"2026-04-22T00:00:00.000Z","next_check":"2026-07-21T00:00:00.000Z","problems":[{"fix":"Ensure that `<script src=\"path/to/jstz.min.js\"></script>` is included in your HTML before any code that tries to use `jstz`.","cause":"The jstz script file was not loaded or executed in the browser environment before attempting to use the `jstz` global object.","error":"ReferenceError: jstz is not defined"},{"fix":"For browsers, load the script via a `<script>` tag. For ESM modules in Node.js, you might need to use `import jstz from 'jstimezonedetect';` with appropriate `type: 'module'` in package.json or rely on a bundler like Webpack or Rollup to handle CommonJS interoperability.","cause":"Attempting to use `require('jstimezonedetect')` in a browser environment or a pure ESM Node.js module without a compatible bundler or transpilation.","error":"ReferenceError: require is not defined"},{"fix":"Verify your import statement (e.g., `const jstz = require('jstimezonedetect');` for CJS) or ensure the global `jstz` object is available in the browser. Check if other scripts are overwriting the `jstz` global.","cause":"The `jstz` object was not correctly imported or exposed, meaning the `determine` method is unavailable.","error":"TypeError: jstz.determine is not a function"}],"ecosystem":"npm","meta_description":null}