Monitor Events and Function Calls via Console

By  on  

Despite having worked on the very complex Firefox for a number of years, I'll always love plain old console.log debugging. Logging can provide an audit trail as events happen and text you can share with others. Did you know that chrome provides monitorEvents and monitor so that you can get a log each time an event occurs or function is called?

Monitor Events

Pass an element and a series of events to monitorEvents to get a console log when the event happens:

// Monitor any clicks within the window
monitorEvents(window, 'click')

// Monitor for keyup and keydown events on the body
monitorEvents(document.body, ['keyup', 'keydown'])

You can pass an array of events to listen for multiple events. The logged event represents the same event you'd see if you manually called addEventListener.

Monitor Function Calls

The monitor method allows you to listen for calls on a specific function:

// Define a sample function
function myFn() { }
// Monitor it
monitor(myFn)

// Usage 1: Basic call
myFn()
// function myFn called

// Usage 2: Arguments
myFn(1)
// function myFn called with arguments: 1

I really like that you can view the arguments provided, which is great for inspecting.

I usually opt for logpoints instead of embedding console statements in code, but monitor and monitorEvents provide an alternative to both.

Recent Features

  • By
    5 Awesome New Mozilla Technologies You’ve Never Heard Of

    My trip to Mozilla Summit 2013 was incredible.  I've spent so much time focusing on my project that I had lost sight of all of the great work Mozillians were putting out.  MozSummit provided the perfect reminder of how brilliant my colleagues are and how much...

  • By
    Serving Fonts from CDN

    For maximum performance, we all know we must put our assets on CDN (another domain).  Along with those assets are custom web fonts.  Unfortunately custom web fonts via CDN (or any cross-domain font request) don't work in Firefox or Internet Explorer (correctly so, by spec) though...

Incredible Demos

  • By
    Introducing MooTools ElementSpy

    One part of MooTools I love is the ease of implementing events within classes. Just add Events to your Implements array and you can fire events anywhere you want -- these events are extremely helpful. ScrollSpy and many other popular MooTools plugins would...

  • By
    Create a Twitter AJAX Button with MooTools, jQuery, or Dojo

    There's nothing like a subtle, slick website widget that effectively uses CSS and JavaScript to enhance the user experience.  Of course widgets like that take many hours to perfect, but it doesn't take long for that effort to be rewarded with above-average user retention and...

Discussion

  1. Oh my chickens, this is amazing!! I can’t tell you how many times I’ve tried to poke around in the Chrome dev tools sources and elements tab trying to find way to listen for events. This is going completely change everything!!

  2. Steve

    It needs to be noted that these are not (yet) universal methods, this only works in Chromium based browsers.

Wrap your code in <pre class="{language}"></pre> tags, link to a GitHub gist, JSFiddle fiddle, or CodePen pen to embed!