Error Monitoring

Capture and track errors in your JavaScript application with Sentry

Error monitoring is the core functionality of Sentry. The SDK automatically captures unhandled errors and allows you to manually capture exceptions with rich context.

Capturing Exceptions

Use captureException() to manually send exceptions to Sentry:

import * as Sentry from '@sentry/browser';

try {
  riskyOperation();
} catch (error) {
  Sentry.captureException(error);
}

With Additional Context

Add extra context when capturing exceptions:

Sentry.captureException(error, {
  level: 'error',
  tags: {
    section: 'checkout',
    payment_method: 'credit_card'
  },
  extra: {
    orderId: '12345',
    amount: 99.99
  }
});

The captureException method returns an event ID that you can use to reference the error later.

Capturing Messages

For non-error events, use captureMessage() to send messages to Sentry:

Sentry.captureMessage('User completed onboarding', 'info');

Severity Levels

Messages support different severity levels:

// Available severity levels
Sentry.captureMessage('Debug info', 'debug');
Sentry.captureMessage('General info', 'info');
Sentry.captureMessage('Warning message', 'warning');
Sentry.captureMessage('Error occurred', 'error');
Sentry.captureMessage('Critical failure', 'fatal');

Capturing Custom Events

For full control, capture custom events with captureEvent():

Sentry.captureEvent({
  message: 'Custom event',
  level: 'info',
  tags: {
    feature: 'beta',
    version: '2.0'
  },
  user: {
    id: 'user-123',
    email: '[e-mail]'
  },
  contexts: {
    custom: {
      action: 'purchase',
      item_count: 3
    }
  }
});

Event IDs

All capture methods return an event ID:

const eventId = Sentry.captureException(error);
console.log(`Error tracked with ID: ${eventId}`);

// Get the last event ID from the isolation scope
const lastEventId = Sentry.lastEventId();

The lastEventId() function returns the last recorded error on the current isolation scope. If another error is captured in between, it will return that one instead.

Checking SDK Status

Verify that Sentry is properly initialized:

// Check if SDK is initialized
if (Sentry.isInitialized()) {
  console.log('Sentry is ready');
}

// Check if SDK is enabled
if (Sentry.isEnabled()) {
  console.log('Sentry is enabled and has a transport');
}

Flushing Events

Manually flush pending events:

// Flush with 2 second timeout
await Sentry.flush(2000);

// Close the SDK and flush all events
await Sentry.close(2000);

Use flush() before your application exits to ensure all events are sent to Sentry.

Error Filtering

Filter errors before they’re sent using the beforeSend callback:

Sentry.init({
  dsn: 'your-dsn',
  beforeSend(event, hint) {
    // Don't send errors from localhost
    if (window.location.hostname === 'localhost') {
      return null;
    }

    // Modify the error before sending
    if (event.exception) {
      console.log('Error being sent:', hint.originalException);
    }

    return event;
  }
});

Next Steps

Scopes

Learn how to use scopes to add context to events

Context

Add rich contextual data to your error reports

Breadcrumbs

Track user actions leading up to errors

Event Processors

Process and modify events before they’re sent