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# Browser Detection
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WebRTC Adapter's browser detection system automatically identifies the WebRTC engine, browser version, and specific capabilities to determine which shims need to be applied.
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## Capabilities
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### Browser Details Object
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The main source of browser information available through `adapter.browserDetails`.
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```javascript { .api }
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interface IBrowserDetails {
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  /** Browser name: 'chrome', 'firefox', 'safari', or 'Not a browser.' */
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  browser: string;
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  /** Browser version number, null if unable to detect */
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  version: number | null;
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  /** Safari-specific: WebRTC Unified Plan support detection */
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  supportsUnifiedPlan?: boolean;
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}
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```
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**Usage Examples:**
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```javascript
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import adapter from 'webrtc-adapter';
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// Check browser type
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switch (adapter.browserDetails.browser) {
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  case 'chrome':
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    console.log('Chrome-based browser detected');
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    break;
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  case 'firefox':
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    console.log('Firefox browser detected');
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    break;
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  case 'safari':
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    console.log('Safari browser detected');
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    break;
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  default:
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    console.log('Unsupported or unknown browser');
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}
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// Check version for feature support
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if (adapter.browserDetails.browser === 'chrome' && adapter.browserDetails.version >= 74) {
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  console.log('Supports modern WebRTC features');
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}
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// Safari-specific capability check
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if (adapter.browserDetails.browser === 'safari' && adapter.browserDetails.supportsUnifiedPlan) {
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  console.log('Safari supports Unified Plan');
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}
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```
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### Detect Browser Function
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Low-level browser detection function that analyzes the user agent string.
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```javascript { .api }
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/**
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 * Detects browser type and version from window object
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 * @param window - Browser window object
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 * @returns Browser details object with detected information
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 */
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function detectBrowser(window: Window): IBrowserDetails;
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```
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**Usage Examples:**
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```javascript
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import { detectBrowser } from 'webrtc-adapter/src/js/utils.js';
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// Manual browser detection
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const browserInfo = detectBrowser(window);
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console.log(`Detected: ${browserInfo.browser} version ${browserInfo.version}`);
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// Custom window object (useful for testing)
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const mockWindow = { navigator: { userAgent: 'Mozilla/5.0...' } };
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const mockBrowserInfo = detectBrowser(mockWindow);
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```
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### Extract Version Function
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Utility function for parsing version numbers from user agent strings using regular expressions.
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```javascript { .api }
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/**
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 * Extract browser version from user agent string
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 * @param uastring - User agent string to parse
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 * @param expr - Regular expression pattern for version extraction
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 * @param pos - Position in regex match array containing version
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 * @returns Parsed version number or null if not found
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 */
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function extractVersion(uastring: string, expr: string, pos: number): number;
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```
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**Usage Examples:**
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```javascript
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import adapter from 'webrtc-adapter';
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// Extract Chrome version
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const chromeVersion = adapter.extractVersion(
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  navigator.userAgent,
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  /Chrom(e|ium)\/(\d+)\./,
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  2
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);
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// Extract Firefox version  
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const firefoxVersion = adapter.extractVersion(
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  navigator.userAgent,
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  /Firefox\/(\d+)\./,
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  1
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);
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// Custom version extraction
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const customVersion = adapter.extractVersion(
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  'MyApp/1.2.3 (Windows)',
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  /MyApp\/(\d+\.\d+\.\d+)/,
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  1
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);
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```
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## Browser Detection Logic
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The detection system uses the following priority order:
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1. **Modern Chrome Detection**: Uses `navigator.userAgentData.brands` when available for Chromium detection
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2. **Firefox Detection**: Checks for `navigator.mozGetUserMedia` presence
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3. **Chrome/Chromium Detection**: Falls back to `navigator.webkitGetUserMedia` or `window.webkitRTCPeerConnection`
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4. **Safari Detection**: Identifies Safari through `window.RTCPeerConnection` + WebKit user agent pattern
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5. **Fallback**: Returns "Not a supported browser" for unrecognized browsers
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## Supported Browsers
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- **Chrome/Chromium**: Includes Chrome, Chromium, Opera, Edge (Chromium-based), and WebView
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- **Firefox**: All Firefox variants with WebRTC support
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- **Safari**: Desktop and mobile Safari with WebRTC capabilities
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- **Unsupported**: Returns appropriate messages for non-WebRTC browsers