Adding Javascript EventListener only if no other listener is present?

Hello,

I'm a relative tyro in the Javascript programming arena, so please go easy on me. :-)

I am trying to add an eventListener to various DOM elements on a page. However, some of the elements I'm adding my event to already have an eventListener, and I don't want to supersede that one; I only want to add my event to an element that doesn't already have an event associated with it.

I've looked through a bunch of stuff relating to addEventListener, event.StopPropagation, event bubbling, and so forth, but haven't figured out any way to accomplish this yet.

Is there a way to detect other event listeners on a given element, or some other way to get where I want?

From stackoverflow

• You can check if the on[event] property of that given element is set by using:

  if (typeof(document.getElementById("element-id").onclick) == "undefined") {
    // event undefined
  }
  
  if (typeof(document.getElementById("element-id").onclick) == "function") {
    // event defined
  }
  

  Notice that this won't work if a javascript library such as jQuery were used to define the event (e.g. by using $("#element-id").click()). I'd recommend you to use jQuery, you can handle events easily with it.

  edit: uh, well, afaik it doesn't work if you're using addEventHandler too. It only works if you set your event by using yourElement.onclick = anyFunction

  Hellion : As it turns out, the event that I'm trying to detect is defined via jQuery (as a live() event). I do have jQuery at my own disposal, but rummaging through the API info at the jQuery.com site, I still don't see anything about detecting pre-existing events, only info on how to bind my own events.

  raphael : oh, in this case: http://stackoverflow.com/questions/1236067/test-if-event-handler-is-bound-to-an-element-in-jquery

  Hellion : thanks, raphael!