Enhance your JavaScript console logging messages

I still remember the day when I discovered that there is a JavaScript console where I could display messages! It was such a relief not having to alert messages anymore, or using a DOM element to display them.

But, what I didn’t know back then was that there are different ways to display messages in the console, apart from the well-known log() method.

I’m going to present the different types of messages that we can use in each major browser, focusing on their visual differences:

In most of the browsers, there are five different methods for styling messages: log(), info(), debug(), warn(), and error(). The log() method is the default in all of them, having the simplest style.

The screenshots are the outcome of the following script that I run into every browser (well, apart from IE, but we’ll get there):


In Chrome, the info() method is the same as log(); the debug() method displays the messages with a blue colour; the warn() method adds a warning sign in front of the message; and the error() method both adds an error sign in front of the message, and changes the text colour to red (also includes a stack trace from where the method was called, but now we’re moving away for the visual discussion).

Here’s a screenshot of the script’s outcome in Chrome 29:

console outcome in Chrome

Before moving to the next browser, Chrome also allows us to style each of the above methods’ text outcome overriding the default styling, using the %c format specifier, as follows:

console.log('%cThis text will now be blue and large', 'color: blue; font-size: x-large');

Moving on, in Opera, log() and debug() methods are the same, info() method’s text is blue, warn() method’s text is orange-yellow-ish (or something like that), and error() method’s text is red. There are no icons.

Here’s a screenshot of the script’s outcome in Opera 12:

console outcome in Opera

In Firefox, all of them (note that although it’s working, the debug() method is deprecated) have the same text colour, but info(), warn(), and error() methods have their own individual icons.

Here’s a screenshot of the script’s outcome in Firefox 21:

console outcome in Firefox

If you are using Internet Explorer 10, don’t use the debug() method, since it will crash your script. The rest of them have different colours and icons.

Here’s a screenshot of the script’s outcome (without debug()) in Internet Explorer 10:

console outcome in Internet Explorer

Finally, in Safari, all apart from the error() method have the same (black) colour, and only warn() and error() methods include icons.

Here’s a screenshot of the script’s outcome in Safari 5:

console outcome in Safari

Console has more power than just custom messages though. I would strongly recommend reading your preferred browser’s documentation about its console API, to discover more.

Here is a list of links to each browser’s documentation:

If you find this useful and you have a Coderwall account, please feel free to upvote it.

Photo by Andrew Lee