JavaScript Error Logging: Everything You Need To Know

JavaScript Error Logging Basic Tips

37.3% of respondents to the 2021 State of JavaScript Survey agreed that developing in JavaScript is “overly complex”.

Since JavaScript is extremely versatile, that adaptability can become too much to handle. The language integrates with too many other tools, so developers can end up with an overwhelming tech stack to simply analyze JavaScript performance and monitor errors.

How can you efficiently debug your code even as it scales up with all the third-party libraries you might use and their associated configurations?

One surprisingly simple but commonly overlooked answer: logging.

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Key Insights

Logging is the practice of recording the alerts and messages that you get about the state of your code. As your application may run into inefficiencies, errors, or even crash, you can save the associated messages together with all the relevant context. 

In this guide, we will go through JavaScript error logging across the following categories:

• Benefits of logging errors in JavaScript
• Client-side vs. server-side logging
• Javascript's built-in logging methods

• Message levels
• Message grouping.

• Recording process length
• Setting the scope of bugs and error handling
• How to track Javascript errors instantly

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Logging Errors in JavaScript

JavaScript’s console can provide you with a wealth of useful information. 

Any message about the performance of your code shows up within the relevant console, helping you:

• Read and understand error messages
• Isolate bugs
• Detect the root cause of a crash.

Yet, all the information within the console deletes itself the second you refresh your app or the specific page associated with the log. 

How can you preserve this context for potential future debugging?

By explicitly logging relevant messages into a more consistent location than just your console.

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Client-Side vs. Server-Side Logging

While your app is in the development phase, every error or alert message about the state of your code is easily accessible to you and your team.

But once you ship to production, certain errors may never show up within your internal system unless you take the time to set up additional logging.

To do so, you should understand the key difference between two types of logging:

• Server-side logging : recording the alerts and messages that you receive from within your internal server and coding environment while testing, debugging, and building your application.
• Client-side logging: capturing and recording the alerts and context around any errors and bugs appearing for your application’s users once you’ve shipped your code to production.

Both categories of logging involve their own best practices and a level of nuance, but in this guide we will focus on how you can set yourself up for server-side logging.

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Javascript's built-in logging methods

For your convenience, a basic server-side logging set-up doesn’t require any additional or third-party tools. JavaScript already comes pre-packaged with several methods within its console object that you can use to capture relevant information.

The main console methods included in JavaScript are:

• console.assert()
• console.clear()
• console.count()
• console.countReset()
• console.debug()
• console.dir()
• console.dirxml()
• console.error()
• console.exception()
• console.group()
• console.groupCollapsed()
• console.groupEnd()
• console.info()
• console.log()
• console.profile()
• console.profileEnd()
• console.table()
• console.time()
• console.timeEnd()
• console.timeStamp()
• console.trace()
• console.warn()

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Message Levels

The messages recorded in your console can encompass multiple levels ranging in severity for your overall application performance. 

Each level is associated with its method within the console:

• console.log(): basic logging operation, which outputs the message as is, without any additional formatting
• console.info(): outputs information messages about application progress, runtime, etc.
• console.warn(): outputs warning messages when your code may have an inefficiency or risk encountering an error
• console.error(): outputs error messages, such as when the code or part of your application crashes.

The exact state and appearance of these messages may change based on the exact browser or environment whose console you’re using:

• Mozilla Firefox
• Google Chrome
• Microsoft Edge
• Safari

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Message Grouping

As your application becomes more complex, the code may end up too difficult to manage.

In this case, you want to organize the alerts on your console into more manageable chunks to search and reference whenever you debug or make other changes.

JavaScript supports two key methods for grouping individual log alerts together:

• console.group(): starts a group of log entries
• console.groupEnd(): ends a group of log entries.

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Recording Process Length: Time Your Code

If you want to understand how long a specific process within your code takes, you can use the corresponding time methods:

• console.time(): use to start the timer before running the specific code that you’d like to analyze.
• console.timeEnd(): use to end the timer at the end of that process.

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This can be useful for catching inefficiencies, analyzing your code’s performance, or tracking down bugs that may be slowing the overall user experience.

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Setting Error Scope: Watch Out For Errors That Will Break Everything

To avoid crashing your entire application, you can use the console for defining the affected scope of a potential error within your code.

The try. . . catch statement can help you map boundaries within your code and program-specific error handling code that will run when the other section of your app crashes. This statement includes 3 blocks:

1. try: the code that runs first. This would be the section of your application that you are testing for errors.
2. catch: error handling code that is only executed when the “try” code crashes.
3. finally: other code which will run afterwards, whether the “try” block was successful or failed.

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How To Instantly Track JavaScript Errors

Proper logging is essential if you hope to catch any JavaScript errors early and to help you with any future debugging.

By properly recording any alerts as they come in, whether in development or production, you can save time for yourself and your team when any problems do pop up.

While the built-in JavaScript logging methods can be powerful, as your application scales, you might also consider a more powerful solution. Additional logging tools can help you organize information and provide you with the complete context around any JavaScript error to track down its root cause.

Railtown AI’s JavaScript error logging and debugging solution  can help you leverage the full power of JavaScript’s error messages with automated insights and alerts powered by AI.

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Ready To Get Started?

If you’re ready to move beyond basic logging and benefit from a robust solution, you can try Railtown AI for free.