Sentry Browser Sdk

Note: SDK versions and APIs below reflect @sentry/browser ≥10.0.0. Always verify against docs.sentry.io/platforms/javascript/ before implementing.

Phase 1: Detect

CRITICAL — Check for frameworks first. Framework-specific SDKs provide significantly better coverage and must be recommended before proceeding with @sentry/browser.

Step 1A: Framework Detection (Redirect If Found)

# Check for React
cat package.json 2>/dev/null | grep -E '"react"'

# Check for Next.js
cat package.json 2>/dev/null | grep '"next"'

# Check for Vue
cat package.json 2>/dev/null | grep '"vue"'

# Check for Angular
cat package.json 2>/dev/null | grep '"@angular/core"'

# Check for Svelte / SvelteKit
cat package.json 2>/dev/null | grep -E '"svelte"|"@sveltejs/kit"'

# Check for Remix
cat package.json 2>/dev/null | grep -E '"@remix-run/react"|"@remix-run/node"'

# Check for Nuxt
cat package.json 2>/dev/null | grep '"nuxt"'

# Check for Astro
cat package.json 2>/dev/null | grep '"astro"'

# Check for Ember
cat package.json 2>/dev/null | grep '"ember-source"'

# Check for Node.js server frameworks (wrong SDK entirely)
cat package.json 2>/dev/null | grep -E '"express"|"fastify"|"@nestjs/core"|"koa"'

If a framework is detected, stop and redirect:

Why redirect matters: Framework SDKs add router-aware transactions, error boundaries, component tracking, and often SSR coverage. Using @sentry/browser directly in a React or Next.js app loses all of that.

Only continue with @sentry/browser if no framework is detected.

Step 1B: Installation Method Detection

# Check if there's a package.json at all (bundler environment)
ls package.json 2>/dev/null

# Check package manager
ls package-lock.json yarn.lock pnpm-lock.yaml bun.lockb 2>/dev/null

# Check build tool
ls vite.config.ts vite.config.js webpack.config.js rollup.config.js esbuild.config.js 2>/dev/null
cat package.json 2>/dev/null | grep -E '"vite"|"webpack"|"rollup"|"esbuild"'

# Check for CMS or static site indicators
ls wp-config.php wp-content/ 2>/dev/null   # WordPress
ls _config.yml _config.yaml 2>/dev/null    # Jekyll
ls config.toml 2>/dev/null                 # Hugo
ls .eleventy.js 2>/dev/null                # Eleventy

# Check for existing Sentry
cat package.json 2>/dev/null | grep '"@sentry/'
grep -r "sentry-cdn.com\|js.sentry-cdn.com" . --include="*.html" -l 2>/dev/null | head -3

What to determine:

Phase 2: Recommend

Present a recommendation based on what you found. Lead with a concrete proposal, don't ask open-ended questions.

Recommended (core coverage):

• ✅ Error Monitoring — always; captures unhandled errors and promise rejections
• ✅ Tracing — recommended for any interactive site; tracks page load and user interactions
• ✅ Session Replay — recommended for user-facing apps; records sessions around errors

Optional (enhanced observability):

• ⚡ User Feedback — capture reports directly from users after errors
• ⚡ Logging — structured logs via Sentry.logger.*; requires npm or CDN logs bundle (not available via Loader Script)
• ⚡ Profiling — JS Self-Profiling API; beta, Chromium-only, requires Document-Policy: js-profiling response header

Feature recommendation logic:

Installation path recommendation:

Propose: "I recommend setting up Error Monitoring + Tracing + Session Replay using Path A (npm). Want me to also add Logging or User Feedback?"

Phase 3: Guide

Path A: npm / yarn / pnpm (Recommended — Bundler Projects)

Install

npm install @sentry/browser --save
# or
yarn add @sentry/browser
# or
pnpm add @sentry/browser

Create src/instrument.ts

Sentry must initialize before any other code runs. Put Sentry.init() in a dedicated sidecar file:

import * as Sentry from '@sentry/browser'

Sentry.init({
  dsn: import.meta.env.VITE_SENTRY_DSN, // Adjust per build tool (see table below)
  environment: import.meta.env.MODE,
  release: import.meta.env.VITE_APP_VERSION, // inject at build time

  sendDefaultPii: true,

  integrations: [
    Sentry.browserTracingIntegration(),
    Sentry.replayIntegration({
      maskAllText: true,
      blockAllMedia: true,
    }),
  ],

  // Tracing
  tracesSampleRate: 1.0, // lower to 0.1–0.2 in production
  tracePropagationTargets: ['localhost', /^https:\/\/yourapi\.io/],

  // Session Replay
  replaysSessionSampleRate: 0.1,
  replaysOnErrorSampleRate: 1.0,

  enableLogs: true,
})

DSN environment variable by build tool:

Entry Point Setup

Import instrument.ts as the very first import in your entry file:

// src/main.ts or src/index.ts
import './instrument' // ← MUST be first

// ... rest of your app

Source Maps Setup (Strongly Recommended)

Without source maps, stack traces show minified code. Set up the build plugin to upload source maps automatically:

No dedicated browser wizard: There is no npx @sentry/wizard -i browser flag. The closest is npx @sentry/wizard@latest -i sourcemaps which configures source map upload only for an already-initialized SDK.

Vite (vite.config.ts):

import { defineConfig } from 'vite'
import { sentryVitePlugin } from '@sentry/vite-plugin'

export default defineConfig({
  build: { sourcemap: 'hidden' },
  plugins: [
    // sentryVitePlugin MUST be last
    sentryVitePlugin({
      org: process.env.SENTRY_ORG,
      project: process.env.SENTRY_PROJECT,
      authToken: process.env.SENTRY_AUTH_TOKEN,
    }),
  ],
})

webpack (webpack.config.js):

const { sentryWebpackPlugin } = require('@sentry/webpack-plugin')

module.exports = {
  devtool: 'hidden-source-map',
  plugins: [
    sentryWebpackPlugin({
      org: process.env.SENTRY_ORG,
      project: process.env.SENTRY_PROJECT,
      authToken: process.env.SENTRY_AUTH_TOKEN,
    }),
  ],
}

Rollup (rollup.config.js):

import { sentryRollupPlugin } from '@sentry/rollup-plugin'

export default {
  output: { sourcemap: 'hidden' },
  plugins: [
    sentryRollupPlugin({
      org: process.env.SENTRY_ORG,
      project: process.env.SENTRY_PROJECT,
      authToken: process.env.SENTRY_AUTH_TOKEN,
    }),
  ],
}

esbuild (build.js):

const { sentryEsbuildPlugin } = require('@sentry/esbuild-plugin')

require('esbuild').build({
  entryPoints: ['src/index.ts'],
  bundle: true,
  sourcemap: 'hidden',
  plugins: [
    sentryEsbuildPlugin({
      org: process.env.SENTRY_ORG,
      project: process.env.SENTRY_PROJECT,
      authToken: process.env.SENTRY_AUTH_TOKEN,
    }),
  ],
})

⚠️ esbuild plugin does not fully support splitting: true. Use sentry-cli instead if code splitting is enabled.

Using sentry-cli (any toolchain / CI):

# After your build step:
npx @sentry/cli sourcemaps inject ./dist
npx @sentry/cli sourcemaps upload ./dist

Add .env for auth (never commit):

SENTRY_AUTH_TOKEN=sntrys_...
SENTRY_ORG=my-org-slug
SENTRY_PROJECT=my-project-slug

Path B: Loader Script (WordPress, Static Sites, Shopify, Squarespace)

Best for: Sites without a build system. The Loader Script is a single <script> tag that lazily loads the full SDK, always stays up to date via Sentry's CDN, and buffers errors before the SDK loads.

Get the Loader Script: Sentry UI → Settings → Projects → (your project) → SDK Setup → Loader Script

Copy the generated tag and place it as the first script on every page:

<!DOCTYPE html>
<html>
  <head>
    <!-- Configure BEFORE the loader tag -->
    <script>
      window.sentryOnLoad = function () {
        Sentry.init({
          // DSN is already configured in the loader URL
          tracesSampleRate: 1.0,
          replaysSessionSampleRate: 0.1,
          replaysOnErrorSampleRate: 1.0,
        })
      }
    </script>

    <!-- Loader Script FIRST — before all other scripts -->
    <script
      src="https://js.sentry-cdn.com/YOUR_PUBLIC_KEY.min.js"
      crossorigin="anonymous"
    ></script>
  </head>
  ...
</html>

Loader loading modes:

Safe to call before SDK loads (buffered):

• Sentry.captureException()
• Sentry.captureMessage()
• Sentry.captureEvent()
• Sentry.addBreadcrumb()
• Sentry.withScope()

For other methods, use Sentry.onLoad():

<script>
  window.Sentry &&
    Sentry.onLoad(function () {
      Sentry.setUser({ id: '123' })
    })
</script>

Set release via global (optional):

<script>
  window.SENTRY_RELEASE = { id: '[email protected]' }
</script>

Loader Script limitations:

• ❌ No Sentry.logger.* (logging) — npm path only
• ❌ No framework-specific features (React ErrorBoundary, Vue Router tracking, etc.)
• ❌ Tracing headers only added to fetch calls made after SDK loads
• ❌ Version changes take a few minutes to propagate via CDN cache
• ⚠️ Use defer (not async) on all other scripts when using the loader

CSP requirements:

script-src: https://browser.sentry-cdn.com https://js.sentry-cdn.com
connect-src: *.sentry.io

Path C: CDN Bundles (Manual Script Tags)

Best for: Pages that can't use the Loader Script but need synchronous loading.

Pick the bundle that matches your feature needs and place it before all other scripts:

Errors only (minimal footprint):

<script
  src="https://browser.sentry-cdn.com/10.42.0/bundle.min.js"
  integrity="sha384-L/HYBH2QCeLyXhcZ0hPTxWMnyMJburPJyVoBmRk4OoilqrOWq5kU4PNTLFYrCYPr"
  crossorigin="anonymous"
></script>

Errors + Tracing:

<script
  src="https://browser.sentry-cdn.com/10.42.0/bundle.tracing.min.js"
  integrity="sha384-DIqcfVcfIewrWiNWfVZcGWExO5v673hkkC5ixJnmAprAfJajpUDEAL35QgkOB5gw"
  crossorigin="anonymous"
></script>

Errors + Session Replay:

<script
  src="https://browser.sentry-cdn.com/10.42.0/bundle.replay.min.js"
  integrity="sha384-sbojwIJFpv9duIzsI9FRm87g7pB15s4QwJS1m1xMSOdV1CF3pwgrPPEu38Em7M9+"
  crossorigin="anonymous"
></script>

Errors + Tracing + Replay (recommended full setup):

<script
  src="https://browser.sentry-cdn.com/10.42.0/bundle.tracing.replay.min.js"
  integrity="sha384-oo2U4zsTxaHSPXJEnXtaQPeS4Z/qbTqoBL9xFgGxvjJHKQjIrB+VRlu97/iXBtzw"
  crossorigin="anonymous"
></script>

Errors + Tracing + Replay + User Feedback:

<script
  src="https://browser.sentry-cdn.com/10.42.0/bundle.tracing.replay.feedback.min.js"
  integrity="sha384-SmHU39Qs9cua0KLtq3A6gis1/cqM1nZ6fnGzlvWAPiwhBDO5SmwFQV65BBpJnB3n"
  crossorigin="anonymous"
></script>

Full bundle (all features):

<script
  src="https://browser.sentry-cdn.com/10.42.0/bundle.tracing.replay.feedback.logs.metrics.min.js"
  integrity="sha384-gOjSzRxwpXpy0FlT6lg/AVhagqrsUrOWUO7jm6TJwuZ9YVHtYK0MBA2hW2FGrIGl"
  crossorigin="anonymous"
></script>

CDN bundle variants summary:

Initialize after the script tag:

<script>
  Sentry.init({
    dsn: 'https://[email protected]/YOUR_PROJECT',
    environment: 'production',
    release: '[email protected]',
    integrations: [
      Sentry.browserTracingIntegration(),
      Sentry.replayIntegration({
        maskAllText: true,
        blockAllMedia: true,
      }),
    ],
    tracesSampleRate: 1.0,
    tracePropagationTargets: ['localhost', /^https:\/\/yourapi\.io/],
    replaysSessionSampleRate: 0.1,
    replaysOnErrorSampleRate: 1.0,
  })
</script>

CDN CSP requirements:

script-src: https://browser.sentry-cdn.com https://js.sentry-cdn.com
connect-src: *.sentry.io

For Each Agreed Feature

Walk through features one at a time. Load the reference file, follow its steps, verify before moving on:

For each feature: Read ${SKILL_ROOT}/references/<feature>.md, follow steps exactly, verify it works.

Configuration Reference

Key Sentry.init() Options

Browser-Specific Options

window.SENTRY_RELEASE Global (CDN / Loader Path)

Set the release version before the SDK loads:

<script>
  window.SENTRY_RELEASE = { id: '[email protected]' }
</script>

Verification

Trigger test events to confirm Sentry is receiving data:

npm / CDN path:

<!-- Add temporarily to your page -->
<button onclick="throw new Error('Sentry Browser Test Error')">
  Test Error
</button>

Performance verification (npm path):

import * as Sentry from '@sentry/browser'

Sentry.startSpan({ name: 'Test Span', op: 'test' }, () => {
  // your operation
})

Manual capture:

Sentry.captureException(new Error('Manual test'))
Sentry.captureMessage('Manual test message', 'info')

Check the Sentry dashboard:

• Issues → error appears within seconds
• Traces → page load transaction visible
• Replays → session recording visible after page interaction
• Logs → structured log entries if logging enabled (npm or CDN logs bundle)

Set debug: true in Sentry.init() and check the browser console if nothing appears.

Phase 4: Cross-Link

After completing browser setup, check for a companion backend missing Sentry coverage:

ls ../backend ../server ../api ../go ../python 2>/dev/null
cat ../go.mod 2>/dev/null | head -3
cat ../requirements.txt ../pyproject.toml 2>/dev/null | head -3
cat ../Gemfile 2>/dev/null | head -3
cat ../pom.xml 2>/dev/null | grep '<artifactId>' | head -3
cat ../composer.json 2>/dev/null | head -3

If a backend exists without Sentry configured, suggest the matching skill:

Troubleshooting