6 Best Javascript Error Logging Basics And Techniques & Tools

Are you tired of navigating the complexities of Vercel Logging, struggling to catch pesky JavaScript errors that seem to slip through the cracks? This blog will study JavaScript Error Logging solutions and best practices, helping you find the perfect tool for your Vercel project.

Alerty's NextJS logging could be the answer if you want to streamline your error-logging process. This solution will help you catch errors before they cause major issues, making your JavaScript error logging a breeze.

Table of Contents

• What Is JavaScript Error Logging?
• Key Components of JavaScript Error Logging
• Why Is JavaScript Error Logging Important?
• Essential Monitoring Services Offered by Alerty
• 6 Best Javascript Error Logging Techniques
• Tools for Error Monitoring
• What To Look Out For In An Error Logging Tool
• Integrating Error Logging Tools With Popular JavaScript Frameworks
• Making Error Reports Actionable By Adding Context (Best Practices For Console Logging)
• Catch Issues Before They Affect Your Users with Alerty's NextJS Logging Tool

What Is JavaScript Error Logging?

JavaScript error logging is the process of capturing, storing and analyzing errors.

This occurs in JavaScript code during web application execution. This practice is essential for maintaining the following: 

• Web application quality
• Performance
• User experience

Key Components of JavaScript Error Logging

Error Capture

This involves detecting and capturing errors when they occur in JavaScript code. Errors can be categorized into three main types:

Runtime Errors

These errors occur during the execution of the code, such as undefined variables or type mismatches.

Syntax Errors

These errors occur due to incorrect syntax in the code and are usually caught at compile time.

Logical Errors

These errors occur when the code doesn't behave as expected despite having correct syntax and runtime behavior.

Error Handling

Once an error is captured, it needs to be handled appropriately. This might involve displaying user-friendly error messages, attempting to recover from the error, or logging the error for further analysis.

Error Reporting

After handling an error, it should be reported to a logging system. This often involves sending the error details to a server or a third-party logging service where it can be stored and analyzed.

Key techniques for JavaScript error monitoring and logging:

• Track errors
• Identify errors
• Handle errors within JavaScript code

When a program encounters an error, whether a syntax mistake, a runtime issue, or a logical error, error monitoring tools help capture and record information about the error.

Related Reading

• NextJS Error Boundary
• Vercel Analytics
• NextJS Opentelemetry
• NextJS Error Handling
• NextJS Error

Why Is JavaScript Error Logging Important?

JavaScript applications have become increasingly complex. These powerful tools now run on various devices in varying network conditions and serve users worldwide. 

Challenges of Scale and Performance

As the demand for feature-rich and responsive web applications continues to grow, developers face new challenges in ensuring their apps' reliability and performance. JavaScript error logging is an essential component for ensuring top-notch user experiences.

Ensuring a Smooth User Experience

Since it’s nearly impossible to catch every issue during development, JavaScript error logging is more critical than ever for identifying and addressing problems before users experience or report them. 

By implementing a robust error-logging strategy, developers can capture real-time data on errors, providing valuable insights for debugging and improving application performance. This helps with:

1. User Experience

Unhandled errors can lead to a poor user experience, causing applications to crash or behave unexpectedly. Logging errors helps developers identify and fix issues promptly, ensuring a smoother experience for users.

2. Debugging and Maintenance

Error logs provide crucial information for debugging. They can include details like the error message, stack trace, browser information, and user actions leading up to the error, making diagnosing and fixing problems easier.

3. Performance Monitoring

Regularly logging and analyzing errors can reveal performance bottlenecks and other issues that may not be immediately apparent, helping to improve the application's overall performance.

4. Proactive Problem Resolution

By monitoring error logs, developers can identify and address issues before they become widespread, leading to more stable and reliable applications.

Essential Monitoring Services Offered by Alerty

Alerty is a cloud monitoring service for developers and early-stage startups, offering:

• Application performance monitoring
• Database monitoring
• Incident management

It supports technologies like NextJS, React, Vue, and Node.js, helping developers identify and fix issues. 

• Alerty monitors databases such as Supabase, PostgreSQL, and RDS
• Tracking key metrics like CPU usage and memory consumption
• It features quick incident management and Real User Monitoring (RUM) to optimize user experience
• Its universal service monitoring covers dependencies like Stripe API, OpenAI, and Vercel. 

Alerty uses AI to simplify setup, providing a cost-effective solution compared to competitors. It is designed for ease of use, allowing quick setup, and integrates with tools like Sentry, making it ideal for developers and small teams needing efficient, affordable monitoring.  

Enhance your application's performance and catch issues before they affect users with Alerty's NextJS logging tool today!

6 Best Javascript Error Logging Techniques

1. Global Error Handlers

Global error handlers allow you to catch and handle errors that occur during the runtime of your JavaScript application. By utilizing window.onerror and window.onunhandledrejection, you can log or report errors and exceptions.

Example:

window.onerror = function(message, url, line, column, error) {

   console.error("An error occurred:", message);

   console.error("URL:", url);

   console.error("Line:", line);

   console.error("Column:", column);

   console.error("Error object:", error);

};

window.onunhandledrejection = function(event) {

   console.error("Unhandled promise rejection:", event.reason);

};

Global Error Handlers in JavaScript

The provided code sets up global error handlers in JavaScript. window.onerror captures unhandled errors and logs the error message, script URL, line and column numbers, and the error object. window.onunhandledrejection captures unhandled promise rejections and logs the rejection reason. These handlers help identify and log errors during a web page's runtime.

2. Try/Catch Blocks

Using try/catch blocks allows you to handle specific exceptions and gracefully recover from errors that might occur within a block of code.

Example:

try {

   // Code that might throw an error

   const result = someFunction();

   console.log("Result:", result);

} catch (error) {

   console.error("An error occurred:", error);

}

Using Try/Catch Blocks for Error Management

The provided code uses a try/catch block to handle potential errors in JavaScript. The try block contains the code that might throw an error, and if an error occurs, the catch block is executed, which logs the error message using console.error().

3. Stack Traces

Stack traces provide valuable information about the sequence of function calls leading to an error. They help understand the error's origin and diagnose the issue effectively.

Example:

function foo() {

   bar();

}

function bar() {

   throw new Error("Something went wrong");

}

try {

   foo();

} catch (error) {

   console.error("Error stack trace:", error.stack);

}

Demonstrating Try/Catch With Error Throwing

The code defines two functions:

• Foo()
• Bar()

When foo() is called, it invokes bar(), which intentionally throws an error using throw new Error(). The code is wrapped in a try/catch block. When an error is thrown within the try block, it is caught by the catch block, and the error object is stored in the error variable. The catch block logs the stack trace of the error using console.error() and the error.stack property.

4. Logging Libraries

Logging libraries like Alerty provide advanced error monitoring features. They simplify error tracking, aggregation, and reporting, and often offer integrations with frameworks and services.

import * as Alerty from '@alerty/browser';

Alerty.init({ dsn: 'YOUR_DSN_HERE' });

try {

  // Some code that may throw an error

  riskyFunction();

} catch (error) {

  Alerty.captureException(error);

}

Capturing and Sending Errors

The code initializes the Alerty logging library and sets up error capturing. Inside the try block, you can place code that may throw an error. If an error occurs, the catch block uses Alety.captureException() to send the error to Alerty for logging and analysis.

5. Custom Error Classes

Extending the built-in Error class allows you to create custom error classes with additional properties and methods. This makes error handling more informative and easier.

Example:

Consider the code shown below.

class MyCustomError extends Error {

   constructor(message, customProperty) {

      super(message);

      this.customProperty = customProperty;

   }

}

try {

   throw new MyCustomError("Something went wrong.", "Custom data");

} catch (error) {

   console.error("Custom property:", error.customProperty);

}

Creating and Catching Custom Errors

The code defines a custom error class MyCustomError that extends Error. Inside the try block, it throws an instance of MyCustomError with a specific error message and custom property. The catch block logs the custom property of the caught error object.

6. Error Reporting and Notifications

Integrate your error monitoring system with notification services like email or chat platforms to receive real-time alerts when critical errors occur.

Example:

Consider the code shown below.

function sendErrorNotification(error) {

   // Code to send an error notification via email or chat

}

try {

   // Code that might throw an error

} catch (error) {

   sendErrorNotification(error);

}

The code defines a function sendErrorNotification() that takes an error parameter and contains the logic to send an error notification, such as via email or chat.

You can place the code within the try block, which may throw an error. If an error occurs, the catch block is executed, and the sendErrorNotification() function is called with the error object as an argument, triggering the error notification process.

This code demonstrates how to handle errors by calling a custom function to send error notifications when an error occurs within the try block. It allows for proactive notification and response to errors, helping to facilitate timely troubleshooting and resolution.

Best Error Logging Tools

Alerty is a cloud monitoring service for developers and early-stage startups, offering:

• Application performance monitoring
• Database monitoring
• Incident management

It supports technologies like NextJS, React, Vue, and Node.js, helping developers identify and fix issues. 

• Alerty monitors databases such as Supabase, PostgreSQL, and RDS
• Tracking key metrics like CPU usage and memory consumption
• It features quick incident management and Real User Monitoring (RUM) to optimize user experience
• Its universal service monitoring covers dependencies like Stripe API, OpenAI, and Vercel. 

Alerty uses AI to simplify setup, providing a cost-effective solution compared to competitors. It is designed for ease of use, allowing quick setup, and integrates with tools like Sentry, making it ideal for developers and small teams needing efficient, affordable monitoring. 

Catch issues before they affect your users with Alerty's NextJS logging tool today! 

Tools for Error Monitoring

LogRocket

It is a comprehensive front-end application monitoring solution that captures errors, performance issues, real user interactions, and more. By providing detailed insights into user experience and application performance, LogRocket enables developers to pinpoint and resolve issues effectively.

Sentry

Sentry is an open-source error-tracking tool that offers real-time monitoring, alerting, and detailed error diagnostics. Its easy-to-use interface and powerful error analysis tools help developers identify, prioritize, and fix application issues.

Rollbar

Rollbar is an error monitoring and analytics platform streamlining error tracking, triage, and resolution. It offers real-time error monitoring, detailed error diagnostics, and customizable alerting options to inform developers about critical issues.

What To Look Out For In An Error Logging Tool

Alerting

Real-time alerts and notifications are crucial for staying informed about issues as they arise. They allow developers to address them quickly and minimize their impact on the user experience. 

Group and Aggregate Issues

Error logging tools should be able to group and aggregate issues, enabling developers to identify the most frequent and severe problems as quickly as possible.

Triage Issues

False positives are inevitable in error logging. It's essential to be able to ignore, classify, and prioritize issues to reduce noise and focus on fixing the most critical problems.

Machine Learning

JavaScript error logging can be noisy, lack context, and make it challenging to discover issues. The best solutions use machine learning to filter out irrelevant data and highlight the most impactful issues affecting your users.

Related Reading

• NextJS Debugger
• NextJS CSRF
• Next JS Best Practices
• NextJS Security
• Javascript Monitoring
• Next JS Speed Optimization

Integrating Error Logging Tools With Popular JavaScript Frameworks

Modern JavaScript error-logging solutions integrate seamlessly with popular JavaScript frameworks to provide tailored error tracking and insights. This integration helps developers to catch, handle, and resolve errors more effectively across: 

• React
• Angular
• Vue

Let's get into how error logging can be incorporated into these major JavaScript frameworks:

React: Error Boundaries

In React, error boundaries are a powerful feature that allows developers to catch JavaScript errors anywhere in their component tree. Error boundaries log errors and display fallback UI instead of crashing the entire component tree. Error boundaries are React components implementing the componentDidCatch(error, info) or getDerivedStateFromError() lifecycle method.

Angular: Extending ErrorHandler

Angular provides a built-in ErrorHandler class that developers can extend to implement custom error-handling logic. Extending this class, you can intercept all errors in your Angular application and send them to an error logging service.

Vue: Global Error Handler

Vue.js lets developers implement a global error handler by adding an errorHandler function to their Vue instance. This function catches all uncaught errors in the component tree and can log these errors to an error logging service. 

Insights and Monitoring

By leveraging these integration methods, developers gain insights into how JavaScript errors affect application performance. Insights include:

• Error frequency
• Impacted user sessions
• Performance bottlenecks, and more

This information helps prioritize and resolve bugs quickly and efficiently, improving application stability and user satisfaction.

Making Error Reports Actionable By Adding Context (Best Practices For Console Logging)

Add Context to Make Logged Errors More Actionable

Adding context to your logs using built-in console methods in a logging application is crucial for making logged errors more actionable. Here are some effective ways to enhance your logs:

Use Appropriate Logging Levels

To better organize logs based on severity level, use various console methods for different purposes:  

• console.log(): General informational messages.  
• console.info(): Important information that provides context.  
• console.warn(): Potential issues that may require attention.  
• console.error(): Errors and critical problems.  

Include Relevant Data

Log relevant data points like user IDs, request IDs, or error codes that provide context about the specific issue. Use string interpolation or template literals to include variables in the log message. For example, `console.log(User ${userId} encountered error ${errorCode})`.

Provide Descriptive Messages

Use clear, descriptive labels in your log messages to indicate what each message represents. Avoid using vague or overly technical language. For instance, use `console.info('Fetching user profile data...')` instead of `console.log('getData')`.

Group Related Logs

Collate related logs together using `console.group()` and `console.groupEnd()`. This creates a collapsible group in the console to organize the logs better. 

For example:

javascript
console.group('User Profile API Request');
console.log('Sending request to /users/123');
console.timeLog('User profile fetch');
console.groupEnd();

Add Timers for Performance

Measure the duration of specific operations using `console.time()` and `console.timeEnd()`. This provides valuable performance insights and helps identify bottlenecks. For example:

javascript
console.time('Rendering homepage');
// render homepage
console.timeEnd('Rendering homepage');

Conditionally Log Errors

Log a message only if a condition is false using `console.assert()`. This is useful for debugging and catching unexpected conditions. For example:

javascript
const isEven = (num) => num % 2 === 0;
console.assert(isEven(3), 'Number is not even');

By leveraging these built-in console methods and best practices, you can add meaningful context to your logs, making it easier to debug issues, monitor performance, and gain insights into your application's behavior. The key is to balance providing sufficient context without overwhelming the logs with unnecessary information.

Catch Issues Before They Affect Your Users with Alerty's NextJS Logging Tool

Alerty is a robust cloud monitoring service designed specifically for developers and early-stage startups. It offers a wide range of monitoring capabilities, including:

• Application performance monitoring
• Database monitoring
• Incident management

This versatile tool supports popular technologies like NextJS, React, Vue, and Node.js, allowing developers to identify and resolve issues efficiently.

Database Performance Monitoring

One of the key features of Alerty is its support for monitoring various databases, such as:

• Supabase
• PostgreSQL
• RDS

Alerty helps developers gain valuable insights into their application's performance and health by tracking essential metrics like CPU usage and memory consumption. This proactive approach enables teams to address potential issues before they impact end users, ensuring a seamless user experience.

Incident Management and Real User Monitoring

Alerty excels in incident management and Real User Monitoring (RUM) to optimize user experience further. By quickly identifying and resolving incidents, teams can minimize downtime and maintain high-performance levels. The RUM feature provides actionable insights into user behavior and preferences, enabling teams to make data-driven decisions to enhance user satisfaction.

Universal Service Monitoring

This monitoring service also offers Universal Service Monitoring, covering dependencies like:

• Stripe API
• OpenAI
• Vercel

By tracking the health and performance of these dependencies, teams can ensure smooth integration and operation of essential services. Alerty leverages AI technology to simplify setup and configuration, providing a cost-effective solution compared to other monitoring tools in the market.

AI-Powered Setup and Cost-Effectiveness

Another crucial aspect of Alerty is its user-friendly interface and seamless integration with other tools like Sentry. This ease of use makes Alerty ideal for developers and small teams looking for efficient and affordable monitoring solutions. Alerty empowers teams to deliver high-quality applications and services consistently by streamlining monitoring processes and enhancing visibility into application performance.

Related Reading

• Datadog NextJS
• Posthog NextJS
• NextJS Prometheus
• Newrelic NextJS
• Front End Monitoring Tools