Vanilla JS · logzai-js/browser

Browser error logging without a framework

logzai-js works in any browser environment. Drop it into a module bundle or use the CDN script tag — zero framework dependencies required.

Get ingest token

npm install logzai-js

No credit card required. 5M events free/month.

What you get out of the box

window.onerror + onunhandledrejection

Captures all unhandled errors and async rejections natively in any browser.

History API route tracking

Wraps pushState and replaceState to log SPA navigations without a framework.

CDN or npm

Works via a <script> tag from CDN or bundled with Webpack, Rollup, or Vite.

Flexible context injection

Inject any global state: window variables, sessionStorage, or cookies.

Cross-origin error filtering

Built-in example to skip the useless 'Script error.' cross-origin events.

logger.js

import logzai, { browserPlugin, spaPlugin } from 'logzai-js/browser'

// Or via CDN: <script src="https://cdn.logzai.com/logzai-js@latest/browser.umd.js"></script>

logzai.init({
  ingestToken: window.__LOGZAI_TOKEN__ || 'YOUR_INGEST_TOKEN',
  ingestEndpoint: 'https://ingest.logzai.com',
  serviceName: 'my-website',
  environment: window.__ENV__ || 'production',
  mirrorToConsole: window.__ENV__ !== 'production',
})

// Capture window.onerror and window.onunhandledrejection
logzai.plugin('browser', browserPlugin, {
  errorFilter: (error) => {
    // Ignore cross-origin script errors (no useful stack trace)
    if (error?.message === 'Script error.') return false
    return true
  },
  contextInjector: () => ({
    userId: window.__currentUser?.id ?? null,
    userEmail: window.__currentUser?.email ?? null,
    currentRoute: window.location.pathname,
    referrer: document.referrer || null,
  }),
})

// Track History API navigation (pushState / replaceState)
logzai.plugin('spa', spaPlugin, {
  logNavigation: true,
  contextInjector: () => ({
    userId: window.__currentUser?.id ?? null,
  }),
})

Every event arrives enriched

When JavaScript captures an error or navigation, LogzAI receives these fields automatically.

Field	Example value	Captured from
serviceName	my-website	logzai.init
environment	production	window.__ENV__
userId	usr_01j8x...	window.__currentUser
userEmail	jane@acme.com	window.__currentUser
currentRoute	/checkout/step-2	window.location.pathname
referrer	https://google.com	document.referrer
message	Uncaught TypeError: ...	window.onerror
level	error	browserPlugin

Start sending events in 2 minutes

Add npm install logzai-js to your JavaScript app and you're done.

No infrastructure to manage. 5M events free/month.

Analyze your logs with AI

Once events are flowing, ask LogzAI questions in plain English. Find root causes in seconds.

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