Parse User Agent

Extract browser, OS, and device information from a user agent string

Code

Utilities

function parseUserAgent(userAgent) {
  const ua = userAgent || navigator.userAgent;

  // Detect browser
  let browser = 'Unknown';
  if (ua.includes('Firefox/')) browser = 'Firefox';
  else if (ua.includes('Edg/')) browser = 'Edge';
  else if (ua.includes('Chrome/')) browser = 'Chrome';
  else if (ua.includes('Safari/') && !ua.includes('Chrome')) browser = 'Safari';
  else if (ua.includes('Opera') || ua.includes('OPR/')) browser = 'Opera';

  // Detect OS
  let os = 'Unknown';
  if (ua.includes('Windows')) os = 'Windows';
  else if (ua.includes('Mac OS')) os = 'macOS';
  else if (ua.includes('Linux')) os = 'Linux';
  else if (ua.includes('Android')) os = 'Android';
  else if (ua.includes('iPhone') || ua.includes('iPad')) os = 'iOS';

  // Detect device type
  let device = 'Desktop';
  if (/Mobile|Android|iPhone|iPad|iPod/i.test(ua)) {
    device = /iPad|Tablet/i.test(ua) ? 'Tablet' : 'Mobile';
  }

  // Extract version
  const versionMatch = ua.match(/(Chrome|Firefox|Safari|Edge|OPR)\/(\d+)/);
  const version = versionMatch ? versionMatch[2] : null;

  return { browser, os, device, version, raw: ua };
}

return parseUserAgent(ua);

Parameters

ua(string)

User agent string (leave empty to use current browser)

Browser·fetch() may be limited by CORS

Example Output

For a Chrome browser on macOS:

{
  "browser": "Chrome",
  "os": "macOS",
  "device": "Desktop",
  "version": "120",
  "raw": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7)..."
}

Common User Agents

Browser	Identifier
Chrome	`Chrome/`
Firefox	`Firefox/`
Safari	`Safari/` (without Chrome)
Edge	`Edg/`
Opera	`OPR/` or `Opera`

Bot Detection

function isBot(userAgent) {
  const botPatterns = [
    /bot/i, /crawl/i, /spider/i, /slurp/i,
    /googlebot/i, /bingbot/i, /yandex/i,
    /facebookexternalhit/i, /twitterbot/i
  ];
  return botPatterns.some(p => p.test(userAgent));
}

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