Capturing Errors

The vij-sdk provides two main APIs for capturing errors and messages: captureException() for error objects and captureMessage() for custom log messages.

captureException()

Capture and send error objects to your VIJ Admin dashboard.

Basic Usage

import { captureException } from "vij-sdk";

try {
  // Code that might throw an error
  const result = riskyOperation();
} catch (error) {
  captureException(error);
}

Signature

captureException(
  error: Error,
  metadata?: Record<string, any>,
  severity?: "error" | "warning" | "info"
): void

Parameters

error

Error

required

The error object to capture. Can be any JavaScript Error instance or object with name, message, and stack properties.Supported Types:

Native JavaScript errors (Error, TypeError, ReferenceError, etc.)
Custom error classes extending Error
Objects with error-like structure

// Native error
captureException(new Error("Something went wrong"));

// Custom error class
class ValidationError extends Error {
  constructor(message) {
    super(message);
    this.name = "ValidationError";
  }
}
captureException(new ValidationError("Invalid email format"));

// Error from catch block
try {
  await fetchData();
} catch (error) {
  captureException(error);
}

metadata

object

default:"{}"

Additional contextual information to attach to this specific error.Use Cases:

User information (ID, email, role)
Request details (URL, method, headers)
Application state at time of error
Feature or component context

captureException(error, {
  userId: "user-123",
  userEmail: "user@example.com",
  feature: "checkout",
  cartTotal: 99.99,
  requestUrl: "/api/payment",
  requestMethod: "POST"
});

Metadata is merged with global metadata from init(). Per-error metadata takes precedence.

severity

string

default:"error"

The severity level of this error.Options:

"error" - Critical errors requiring immediate attention
"warning" - Non-critical issues that should be investigated
"info" - Informational logs for tracking behavior

// Critical error
captureException(error, { feature: "payment" }, "error");

// Non-critical warning
captureException(deprecationError, { api: "legacy" }, "warning");

// Informational
captureException(new Error("Rate limit approaching"), {}, "info");

Severity levels help you filter and prioritize errors in the dashboard.

Automatic Error Capture

The SDK automatically captures uncaught errors and unhandled promise rejections without any additional code:

Browser
Node.js

// Automatically captured - no try/catch needed
window.addEventListener("click", () => {
  throw new Error("Button click error"); // Captured automatically
});

// Unhandled promise rejection - automatically captured
fetch("/api/data").then(response => {
  throw new Error("Processing failed"); // Captured automatically
});

Browser Events Captured:

window.onerror - Uncaught exceptions
window.onunhandledrejection - Unhandled promise rejections

// Automatically captured - no try/catch needed
process.nextTick(() => {
  throw new Error("Async error"); // Captured automatically
});

// Unhandled promise rejection - automatically captured
Promise.reject(new Error("Rejected promise")); // Captured automatically

Node.js Events Captured:

process.on("uncaughtException") - Uncaught exceptions
process.on("unhandledRejection") - Unhandled promise rejections

While automatic capture is convenient, it’s better to explicitly catch and handle errors in production code. Use captureException() in catch blocks for better control.

Advanced Examples

Capturing with Rich Metadata

import { captureException } from "vij-sdk";

async function processPayment(userId, amount) {
  try {
    const payment = await stripeAPI.charge({ userId, amount });
    return payment;
  } catch (error) {
    captureException(error, {
      // User context
      userId: userId,
      userPlan: "premium",

      // Transaction context
      paymentAmount: amount,
      currency: "USD",

      // Application state
      cartItems: 5,
      discountApplied: true,

      // Technical details
      stripeApiVersion: "2023-10-16",
      timestamp: new Date().toISOString()
    });

    throw error; // Re-throw after capturing
  }
}

Capturing Errors in React Components

import { captureException } from "vij-sdk";
import { Component } from "react";

class ErrorBoundary extends Component {
  componentDidCatch(error, errorInfo) {
    captureException(error, {
      componentStack: errorInfo.componentStack,
      route: window.location.pathname,
      userAgent: navigator.userAgent
    });
  }

  render() {
    return this.props.children;
  }
}

Capturing Errors in Express Middleware

import { captureException } from "vij-sdk";

app.use((err, req, res, next) => {
  captureException(err, {
    requestUrl: req.originalUrl,
    requestMethod: req.method,
    requestHeaders: req.headers,
    requestBody: req.body,
    userId: req.user?.id,
    ipAddress: req.ip
  });

  res.status(500).json({ error: "Internal server error" });
});

captureMessage()

Capture custom log messages without an error object.

Basic Usage

import { captureMessage } from "vij-sdk";

captureMessage("User logged in successfully");

Signature

captureMessage(
  message: string,
  metadata?: Record<string, any>,
  severity?: "error" | "warning" | "info"
): void

Parameters

message

string

required

The log message to capture.Best Practices:

Use clear, descriptive messages
Include relevant details in the message or metadata
Keep messages concise but informative

// Good
captureMessage("Payment processed successfully for order #12345");

// Better - use metadata
captureMessage("Payment processed successfully", { orderId: 12345 });

metadata

object

default:"{}"

Additional contextual information to attach to this message.

captureMessage("User action", {
  action: "button_click",
  buttonId: "checkout",
  userId: "user-123",
  timestamp: Date.now()
});

severity

string

default:"info"

The severity level of this message.Options:

"info" - Informational messages (default for captureMessage)
"warning" - Warning messages
"error" - Error messages

// Info level (default)
captureMessage("User logged in", { userId: "123" }, "info");

// Warning level
captureMessage("Rate limit approaching", { requestCount: 950 }, "warning");

// Error level
captureMessage("Configuration missing", { key: "API_KEY" }, "error");

Use Cases

User Actions
System Events
Performance Monitoring
Business Logic

import { captureMessage } from "vij-sdk";

function trackUserAction(action, details) {
  captureMessage(`User action: ${action}`, {
    userId: details.userId,
    actionType: action,
    timestamp: new Date().toISOString(),
    ...details
  }, "info");
}

// Track button clicks
trackUserAction("checkout_clicked", {
  userId: "user-123",
  cartValue: 99.99
});

// Track form submissions
trackUserAction("form_submitted", {
  formId: "contact-form",
  fields: 5
});

import { captureMessage } from "vij-sdk";

// Database connection
captureMessage("Database connected successfully", {
  host: "mongodb.example.com",
  database: "production",
  connectTime: 1234
}, "info");

// Cache operations
captureMessage("Cache hit", {
  key: "user:123",
  ttl: 3600
}, "info");

// Scheduled tasks
captureMessage("Cron job completed", {
  job: "daily-report",
  duration: 5432,
  recordsProcessed: 10000
}, "info");

import { captureMessage } from "vij-sdk";

function trackPerformance(operation, duration) {
  const severity = duration > 5000 ? "warning" : "info";

  captureMessage(`Performance: ${operation}`, {
    operation,
    duration,
    threshold: 5000,
    exceeded: duration > 5000
  }, severity);
}

// Track API response times
const start = Date.now();
await fetchData();
trackPerformance("fetchData", Date.now() - start);

import { captureMessage } from "vij-sdk";

// Track important business events
captureMessage("Order placed", {
  orderId: "ORD-12345",
  userId: "user-123",
  total: 199.99,
  items: 3,
  paymentMethod: "credit_card"
}, "info");

// Track threshold events
if (inventoryCount < 10) {
  captureMessage("Low inventory warning", {
    productId: "PROD-456",
    currentStock: inventoryCount,
    threshold: 10
  }, "warning");
}

Contextual Information

Both captureException() and captureMessage() automatically collect rich contextual information:

Browser Context

{
  "viewport": {
    "width": 1920,
    "height": 1080
  },
  "screen": {
    "width": 1920,
    "height": 1080,
    "colorDepth": 24
  },
  "browser": {
    "userAgent": "Mozilla/5.0...",
    "language": "en-US",
    "platform": "MacIntel",
    "cookieEnabled": true,
    "doNotTrack": "1"
  },
  "network": {
    "effectiveType": "4g",
    "downlink": 10,
    "rtt": 50
  }
}

Node.js Context

{
  "process": {
    "pid": 12345,
    "platform": "linux",
    "arch": "x64",
    "nodeVersion": "v20.0.0",
    "uptime": 3600,
    "memory": {
      "rss": 50000000,
      "heapTotal": 30000000,
      "heapUsed": 20000000,
      "external": 1000000
    }
  }
}

This context is collected automatically. You don’t need to add it manually.

Best Practices

Always include relevant metadata

Add contextual information that will help debug the issue:

// Good
captureException(error, {
  userId: user.id,
  feature: "checkout",
  step: "payment",
  paymentMethod: "stripe"
});

// Bad
captureException(error); // Missing context

Use appropriate severity levels

Error: Critical issues requiring immediate attention

captureException(paymentError, { orderId: 123 }, "error");

Warning: Issues that should be investigated but aren’t critical

captureException(deprecatedApiWarning, {}, "warning");

Info: Tracking and informational purposes

captureMessage("Feature flag enabled", { flag: "new-ui" }, "info");

Avoid capturing sensitive data

Never log passwords, tokens, or PII without sanitization:

// Bad
captureException(error, {
  password: user.password, // Never log passwords!
  creditCard: user.card // Never log card numbers!
});

// Good
captureException(error, {
  userId: user.id, // Use IDs instead
  hasPaymentMethod: !!user.card // Use boolean flags
});

Don't capture errors in tight loops

Avoid overwhelming your VIJ instance with duplicate errors:

// Bad
for (let i = 0; i < 10000; i++) {
  try {
    processItem(i);
  } catch (error) {
    captureException(error); // Will create 10000 errors!
  }
}

// Good - batch errors or add deduplication
const errors = [];
for (let i = 0; i < 10000; i++) {
  try {
    processItem(i);
  } catch (error) {
    errors.push({ index: i, error });
  }
}
if (errors.length > 0) {
  captureException(new Error(`Batch processing failed`), {
    failedCount: errors.length,
    totalItems: 10000
  });
}

Re-throw errors after capturing

Capture the error but don’t swallow it:

// Good
try {
  await criticalOperation();
} catch (error) {
  captureException(error, { operation: "critical" });
  throw error; // Re-throw for upstream handling
}

// Bad
try {
  await criticalOperation();
} catch (error) {
  captureException(error);
  // Swallowed! Upstream code won't know about the error
}

Integration Patterns

React Error Boundary

import { Component } from "react";
import { captureException } from "vij-sdk";

class ErrorBoundary extends Component {
  state = { hasError: false };

  static getDerivedStateFromError(error) {
    return { hasError: true };
  }

  componentDidCatch(error, errorInfo) {
    captureException(error, {
      componentStack: errorInfo.componentStack,
      route: window.location.pathname
    });
  }

  render() {
    if (this.state.hasError) {
      return <h1>Something went wrong.</h1>;
    }
    return this.props.children;
  }
}

Vue Error Handler

import { createApp } from "vue";
import { captureException } from "vij-sdk";

const app = createApp(App);

app.config.errorHandler = (err, instance, info) => {
  captureException(err, {
    componentName: instance?.$options?.name,
    errorInfo: info,
    route: window.location.pathname
  });
};

app.mount("#app");

Express Error Middleware

import express from "express";
import { captureException } from "vij-sdk";

const app = express();

// Routes...

// Error handling middleware (must be last)
app.use((err, req, res, next) => {
  captureException(err, {
    url: req.originalUrl,
    method: req.method,
    headers: req.headers,
    body: req.body,
    params: req.params,
    query: req.query,
    userId: req.user?.id
  });

  res.status(500).json({ error: "Internal server error" });
});

Async/Await Error Handling

import { captureException } from "vij-sdk";

async function fetchUserData(userId) {
  try {
    const response = await fetch(`/api/users/${userId}`);

    if (!response.ok) {
      throw new Error(`HTTP ${response.status}: ${response.statusText}`);
    }

    return await response.json();
  } catch (error) {
    captureException(error, {
      operation: "fetchUserData",
      userId,
      timestamp: new Date().toISOString()
    });

    throw error;
  }
}

Troubleshooting

Errors not appearing in dashboard

Check the following:

Verify init() was called before captureException()
Check browser console/server logs for network errors
Ensure VIJ Admin endpoint is accessible
Verify batching settings aren’t delaying delivery too long
Check that error object has name, message, and stack properties

Debug: Disable batching for immediate delivery

init({ batch: false, /* ... */ });

Duplicate errors appearing

Cause: Same error being captured multiple timesSolutions:

Check if error is being captured in both automatic handlers and manual try/catch
Implement deduplication logic for recurring errors
Use error grouping features in VIJ Admin dashboard

Learn more about error grouping →

Metadata not appearing

Issue: Custom metadata not showing in dashboardSolution: Ensure metadata is JSON-serializable

// Bad - circular reference
const obj = { name: "test" };
obj.self = obj;
captureException(error, { obj }); // Will fail

// Good
captureException(error, { name: "test", id: 123 });

Next Steps

SDK Configuration

Learn about all available SDK configuration options

API Reference

Explore the complete SDK API documentation

Error Grouping

Understand how VIJ groups similar errors

Dashboard Features

Explore VIJ Admin dashboard features

Getting started

SDK

Dashboard

Advanced

​captureException()

​Basic Usage

​Signature

​Parameters

​Automatic Error Capture

​Advanced Examples

​Capturing with Rich Metadata

​Capturing Errors in React Components

​Capturing Errors in Express Middleware

​captureMessage()

​Basic Usage

​Signature

​Parameters

​Use Cases

​Contextual Information

​Browser Context

​Node.js Context

​Best Practices

​Integration Patterns

​React Error Boundary

​Vue Error Handler

​Express Error Middleware

​Async/Await Error Handling

​Troubleshooting

​Next Steps

SDK Configuration

API Reference

Error Grouping

Dashboard Features

captureException()

Basic Usage

Signature

Parameters

Automatic Error Capture

Advanced Examples

Capturing with Rich Metadata

Capturing Errors in React Components

Capturing Errors in Express Middleware

captureMessage()

Basic Usage

Signature

Parameters

Use Cases

Contextual Information

Browser Context

Node.js Context

Best Practices

Integration Patterns

React Error Boundary

Vue Error Handler

Express Error Middleware

Async/Await Error Handling

Troubleshooting

Next Steps