Web SDK Compatibility

Supported Browsers

Flashcat RUM Web SDK supports the following browsers and versions:

Browser	Desktop	Mobile	Minimum Version	Notes
Chrome	✅	✅	63+	Full support for all features
Firefox	✅	-	67+	Some features limited (see below)
Safari	✅	✅	12.1+	Some features limited (see below)
Edge	✅	-	79+	Chromium-based version
Opera	✅	-	50+	Full support for all features
Internet Explorer	❌	-	-	Not supported

Note: Internet Explorer 11 and earlier versions are not supported.

Browser Feature Compatibility

The following table details each browser's support for SDK features:

Feature	Chrome	Firefox	Safari	Edge	Chrome Android	Safari iOS	Opera
SDK Loading	✅	✅	✅	✅	✅	✅	✅
SDK Initialization	✅	✅	✅	✅	✅	✅	✅
RUM Data Reporting	✅	✅	✅	✅	✅	✅	✅
Flush on Page Hide	✅	✅	✅	✅	✅	❌	✅
Console Error Capture	✅	✅	✅	✅	✅	✅	✅
Runtime Error Capture	✅	✅	✅	✅	✅	✅	✅
CSP Violation Detection	✅	✅	✅	✅	✅	✅	✅
Browser Intervention Detection	✅	❌	❌	✅	✅	❌	✅
Automatic Action Tracking	✅	✅	✅	✅	✅	✅	✅
Custom Action Tracking	✅	✅	✅	✅	✅	✅	✅
Long Task Detection	✅	❌	❌	✅	✅	❌	✅
Distributed Tracing	✅	✅	✅	✅	✅	✅	✅
Route Change Tracking	✅	✅	✅	✅	✅	✅	✅
Page Load Time	✅	✅	✅	✅	✅	✅	✅
Resource Performance Monitoring	✅	✅	⚠️ (1)	✅	✅	⚠️ (1)	✅
Navigation Performance Monitoring	✅	✅	✅	✅	✅	✅	✅
Web Vitals	✅	⚠️ (2)	⚠️ (2)	✅	✅	⚠️ (2)	✅
FCP (First Contentful Paint)	✅	✅	✅	✅	✅	✅	✅

Notes:

Resource size information unavailable

Only supports FID (First Input Delay) metric

Framework Compatibility

JavaScript Frameworks

Framework/Library	Auto-tracking	Manual Tracking	Notes
React	✅	✅	Supports React 16.8+ (Hooks)
Vue.js	✅	✅	Supports Vue 2.x and Vue 3.x
Angular	✅	✅	Supports Angular 12+
Next.js	✅	✅	Supports SSR and client-side rendering
Nuxt.js	✅	✅	Supports SSR and client-side rendering
Svelte	⚠️	✅	Requires additional configuration for auto-tracking
Vanilla JS	-	✅	Native JavaScript, full manual tracking support

Build Tools

Tool	Support Status	Notes
Webpack	✅	Supports all mainstream versions (4.x, 5.x)
Vite	✅	Recommended
Rollup	✅	Full support
Parcel	✅	Full support
esbuild	✅	Full support
Turbopack	✅	Experimental support

Module Systems

Module System	Support Status	Notes
ES Module (ESM)	✅	Recommended
CommonJS (CJS)	✅	Full support
UMD	✅	Suitable for direct browser inclusion

Network Request Library Compatibility

Library/API	Auto-tracking	Manual Tracking	Notes
Fetch API	✅	✅	Requires enabling auto-tracking configuration
XMLHttpRequest	✅	✅	Requires enabling auto-tracking configuration
Axios	✅	✅	Auto-tracking via interceptors
jQuery.ajax	⚠️	✅	Based on XMLHttpRequest, requires configuration

Web API Dependencies

SDK depends on the following Web APIs, please ensure target browsers support them:

Required APIs

API	Purpose	Fallback
`navigator.sendBeacon`	Send data on page unload	Use Fetch API
`fetch`	Data reporting	None
`Promise`	Async processing	None
`JSON`	Data serialization	None

Optional APIs

API	Purpose	Impact When Missing
`PerformanceObserver`	Performance monitoring	Some performance metrics unavailable
`PerformanceNavigationTiming`	Navigation performance data	Cannot obtain navigation performance metrics
`PerformanceResourceTiming`	Resource loading performance data	Cannot obtain resource performance metrics
`IntersectionObserver`	Element visibility detection	Some user behavior tracking affected
`MutationObserver`	DOM change monitoring	Some auto-tracking features affected
`PerformanceLongTaskTiming`	Long task detection	Cannot detect long tasks
`visibilitychange` event	Page visibility change detection	Some session tracking features affected

TypeScript Support

TypeScript Version	Support Status	Notes
4.0+	✅	Provides complete type definitions
3.8 - 3.9	⚠️	Basic support, some types limited
< 3.8	❌	Not supported

SDK provides complete TypeScript type definition files (.d.ts), supporting IntelliSense and type checking.

Content Security Policy (CSP)

If your website uses CSP, you need to add the following configuration to your CSP policy:

Content-Security-Policy:
  connect-src 'self' https://rum-intake.flashcat.cloud;
  script-src 'self' 'unsafe-inline';

Privacy and Security

SDK may use the following types of storage:

Storage Type	Purpose	Required
localStorage	Session state persistence	Optional
sessionStorage	Temporary session data	Optional
Cookie	User identification (configurable)	Optional

Cookies and local storage can be disabled through configuration, using pure memory mode.

SDK uses SameSite=Lax policy by default, compatible with modern browser privacy requirements.

Known Limitations

Safari Limitations

Long task detection unavailable: Safari doesn't support Long Tasks API

Some Web Vitals metrics limited: Only supports FID, doesn't support full measurement of CLS and LCP

Resource size information: Some resource size information may be inaccurate

iOS Safari flush on hide: Data may not be immediately sent when page is hidden

Firefox Limitations

Long task detection unavailable: Firefox doesn't support Long Tasks API

Browser intervention detection unavailable: Firefox doesn't support Intervention API

Some Web Vitals metrics limited: Only supports FID

Mobile Browser Limitations

Background execution restrictions: Mobile browsers may pause JavaScript execution when in background

Memory limitations: Mobile device memory constraints may affect data caching capability

Network limitations: Unstable mobile networks may cause data reporting delays

Single Page Applications (SPA)

Need to enable route change tracking configuration

Some framework routing libraries require additional configuration

Performance Impact

Flashcat Web SDK is designed to be lightweight with minimal impact on web performance:

SDK size: Approximately 30 KB (about 10 KB after gzip)

Runtime memory usage: < 2 MB

CPU usage: < 1%

First load impact: < 50ms

Update Strategy

Major version updates: May contain incompatible changes requiring code adjustments

Minor version updates: New features, backward compatible

Patch version updates: Bug fixes, fully backward compatible

Regular updates to the latest stable SDK version are recommended for optimal performance and security.

Minimum Deployment Requirements

To ensure SDK works properly, please verify:

Browser versions:

Chrome 63+

Firefox 67+

Safari 12.1+

Edge 79+

JavaScript support: ES6+ (ES2015)

Required Web APIs:

fetch API

Promise

JSON

Network access: App needs to access https://rum-intake.flashcat.cloud to report data

HTTPS: Recommended to use in HTTPS environment for full feature support

Web SDK Integration Guide: Learn how to integrate the SDK

Web SDK Advanced Configuration: Learn about SDK advanced configuration options

Web SDK Data Collection: Learn what data the SDK collects

Compatibility

Supported Browsers#

Browser Feature Compatibility#

Framework Compatibility#

JavaScript Frameworks#

Build Tools#

Module Systems#

Network Request Library Compatibility#

Web API Dependencies#

Required APIs#

Optional APIs#

TypeScript Support#

Content Security Policy (CSP)#

Privacy and Security#

Cookie Usage#

SameSite Cookie#

Known Limitations#

Safari Limitations#

Firefox Limitations#

Mobile Browser Limitations#

Single Page Applications (SPA)#

Performance Impact#

Update Strategy#

Minimum Deployment Requirements#

Related Documentation#