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How to find out which JavaScript events fired?

Posted by: admin November 30, 2017 Leave a comment


I have a select list:

<select id="filter">
  <option value="Open" selected="selected">Open</option>
  <option value="Closed">Closed</option>

When I select Closed the page reloads. In this case it shows closed tickets (instead of opened). It works fine when I do it manually.

The problem is that the page does not reload when I select Closed with Watir:

browser.select_list(:id => "filter").select "Closed"

That usually means that some JavaScript event is not fired. I can fire events with Watir:

browser.select_list(:id => "filter").fire_event "onclick"

but I need to know which event to fire.

Is there a way to find out which events are defined for an element?


Looks like Firebug (Firefox add-on) has the answer:

  • open Firebug
  • right click the element in HTML tab
  • click Log Events
  • enable Console tab
  • click Persist in Console tab (otherwise Console tab will clear after the page is reloaded)
  • select Closed (manually)
  • there will be something like this in Console tab:

    mousemove clientX=1097, clientY=292
    mousedown clientX=1097, clientY=292
    mouseup clientX=1097, clientY=292
    click clientX=1097, clientY=292
    mousemove clientX=1096, clientY=293

Source: Firebug Tip: Log Events


Just thought I’d add that you can do this in Chrome as well:

Ctrl + Shift + I (Developer Tools) > Sources> Event Listener Breakpoints (on the right).

You can also view all events that have already been attached by simply right clicking on the element and then browsing its properties (the panel on the right).

For example:

  • Right click on the upvote button to the left
  • Select inspect element
  • Collapse the styles section (section on the far right – double chevron)
  • Expand the event listeners option
  • Now you can see the events bound to the upvote
  • Not sure if it’s quite as powerful as the firebug option, but has been enough for most of my stuff.

    Another option that is a bit different but surprisingly awesome is Visual Event:

    It highlights all of the elements on a page that have been bound and has popovers showing the functions that are called. Pretty nifty for a bookmark! There’s a Chrome plugin as well if that’s more your thing – not sure about other browsers.

    AnonymousAndrew has also pointed out monitorEvents(window); here


    Regarding Chrome, checkout the monitorEvents() via the command line API.

    • Open the console via Menu > Tools > JavaScript Console.
    • Enter monitorEvents(window);
    • View the console flooded with events

      mousemove MouseEvent {dataTransfer: ...}
      mouseout MouseEvent {dataTransfer: ...}
      mouseover MouseEvent {dataTransfer: ...}
      change Event {clipboardData: ...}

    There are other examples in the documentation. I’m guessing this feature was added after the previous answer.