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This document details the browsers, frameworks, build tools, and related limitations supported by Web RUM SDK, helping you evaluate SDK applicability in your target environment.

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Supported Browsers

BrowserDesktopMobileMin VersionNotes
Chrome✅✅63+Full feature support
Firefox✅-67+Some features limited (see below)
Safari✅✅12.1+Some features limited (see below)
Edge✅-79+Chromium-based version
Opera✅-50+Full feature support
Internet Explorer❌--Not supported
Internet Explorer 11 and earlier versions are not supported.

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Browser Feature Compatibility

The following table details SDK feature support across browsers:
FeatureChromeFirefoxSafariEdgeChrome AndroidSafari iOSOpera
SDK Loading✅✅✅✅✅✅✅
SDK Initialization✅✅✅✅✅✅✅
RUM Data Reporting✅✅✅✅✅✅✅
Page Hidden Flush✅✅✅✅✅❌✅
Console Error Capture✅✅✅✅✅✅✅
Runtime Error Capture✅✅✅✅✅✅✅
CSP Violation Detection✅✅✅✅✅✅✅
Browser Intervention Detection✅❌❌✅✅❌✅
Auto Action Tracking✅✅✅✅✅✅✅
Custom Action Tracking✅✅✅✅✅✅✅
Long Task Detection✅❌❌✅✅❌✅
Distributed Tracing✅✅✅✅✅✅✅
Route Change Tracking✅✅✅✅✅✅✅
Page Load Time✅✅✅✅✅✅✅
Resource Performance✅✅⚠️ (1)✅✅⚠️ (1)✅
Navigation Performance✅✅✅✅✅✅✅
Web Vitals✅⚠️ (2)⚠️ (2)✅✅⚠️ (2)✅
FCP (First Contentful Paint)✅✅✅✅✅✅✅
Notes:
  1. Resource size information unavailable
  2. Only FID (First Input Delay) metric supported

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Framework Compatibility

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JavaScript Frameworks

React

Supports React 16.8+ (Hooks), auto tracking ✅

Vue.js

Supports Vue 2.x and Vue 3.x, auto tracking ✅

Angular

Supports Angular 12+, auto tracking ✅

Next.js

Supports SSR and client-side rendering, auto tracking ✅

Nuxt.js

Supports SSR and client-side rendering, auto tracking ✅

Svelte

Requires additional configuration for auto tracking ⚠️
Vanilla JavaScript fully supports manual tracking features.

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Build Tools

ToolSupport StatusNotes
Webpack✅Supports all major versions (4.x, 5.x)
Vite✅Recommended
Rollup✅Full support
Parcel✅Full support
esbuild✅Full support
Turbopack✅Experimental support

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Module Systems

Module SystemSupport StatusNotes
ES Module (ESM)✅Recommended
CommonJS (CJS)✅Full support
UMD✅Suitable for direct browser import

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Network Request Library Compatibility

Library/APIAuto TrackingManual TrackingNotes
Fetch API✅✅Requires auto tracking configuration enabled
XMLHttpRequest✅✅Requires auto tracking configuration enabled
Axios✅✅Auto tracking via interceptors
jQuery.ajax⚠️✅Based on XMLHttpRequest, requires configuration

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Web API Dependencies

The SDK depends on the following Web APIs. Please ensure target browsers support them:

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Required APIs

APIPurposeFallback
navigator.sendBeaconSend data on page unloadUses Fetch API
fetchData reportingNone
PromiseAsync handlingNone
JSONData serializationNone

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Optional APIs

APIPurposeImpact When Missing
PerformanceObserverPerformance monitoringSome performance metrics unavailable
PerformanceNavigationTimingNavigation performance dataCannot get navigation performance metrics
PerformanceResourceTimingResource loading performance dataCannot get resource performance metrics
IntersectionObserverElement visibility detectionSome user behavior tracking affected
MutationObserverDOM change monitoringSome auto tracking features affected
PerformanceLongTaskTimingLong task detectionCannot detect long tasks
visibilitychange eventPage visibility change detectionSome session tracking features affected

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TypeScript Support

TypeScript VersionSupport StatusNotes
4.0+✅Complete type definitions provided
3.8 - 3.9⚠️Basic support, some types limited
< 3.8❌Not supported
The SDK provides complete TypeScript type definition files (.d.ts), supporting IntelliSense and type checking.

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Content Security Policy (CSP)

If your website uses CSP, add the following to your CSP policy:
CSP Configuration
Content-Security-Policy:
  connect-src 'self' https://rum-intake.flashcat.cloud;
  script-src 'self' 'unsafe-inline';
If using CDN integration, also add https://static.flashcat.cloud to script-src.

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Privacy and Security

The SDK may use the following storage types:
Storage TypePurposeRequired
localStorageSession state persistenceOptional
sessionStorageTemporary session dataOptional
CookieUser identification (configurable)Optional
Cookies and local storage can be disabled via configuration to use pure memory mode. The SDK uses SameSite=Lax policy by default, compatible with modern browser privacy requirements.

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Known Limitations

LimitationDescription
Long Task DetectionSafari doesn’t support Long Tasks API
Web VitalsOnly FID supported, CLS and LCP full measurement not supported
Resource Size InformationSome resource size information may be inaccurate
Data Send on Page HiddeniOS Safari cannot guarantee immediate data send when page is hidden
LimitationDescription
Long Task DetectionFirefox doesn’t support Long Tasks API
Browser Intervention DetectionFirefox doesn’t support Intervention API
Web VitalsOnly FID supported
  • Background Running 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
  • Route change tracking configuration needs to be enabled
  • Some framework routing libraries require additional configuration
  • Recommend manually calling startView method to track route changes
See Advanced Configuration for detailed SPA route tracking configuration.

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Performance Impact

FlashCat Web SDK is designed to be lightweight with minimal impact on webpage performance:
  • SDK Size: ~30 KB (~10 KB gzipped)
  • Runtime Memory Usage: < 2 MB
  • CPU Usage: < 1%
  • First Load Impact: < 50ms

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Update Strategy

  • Major Version Updates: May contain breaking changes, code adjustments required
  • Minor Version Updates: New features, backward compatible
  • Patch Version Updates: Bug fixes, fully backward compatible
We recommend regularly updating the SDK to the latest stable version for best performance and security.

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Minimum Deployment Requirements

To ensure the SDK works properly, please ensure:
  1. Browser Versions:
    • Chrome 63+
    • Firefox 67+
    • Safari 12.1+
    • Edge 79+
  2. JavaScript Support: ES6+ (ES2015)
  3. Required Web APIs:
    • fetch API
    • Promise
    • JSON
  4. Network Access: Application needs to access https://rum-intake.flashcat.cloud for data reporting
  5. HTTPS: Recommended to use in HTTPS environment for full feature support

SDK Integration Guide

Learn how to integrate the SDK

Advanced Configuration

Learn about advanced SDK configuration options

Data Collection

Learn what data the SDK collects