jQuery find events handlers registered with an object

I need to find which event handlers are registered over an object.

For example:

$("#el").click(function() {...});
$("#el").mouseover(function() {...});

$("#el") has click and mouseover registered.

Is there a function to find out that, and possibly iterate over the event handlers?

If it is not possible on a jQuery object through proper methods, is it possible on a plain DOM object?

As of jQuery 1.8, the event data is no longer available from the "public API" for data. Read this jQuery blog post. You should now use this instead:

jQuery._data( elem, "events" );

elem should be an HTML Element, not a jQuery object, or selector.

Please note, that this is an internal, 'private' structure, and shouldn't be modified. Use this for debugging purposes only.

In older versions of jQuery, you might have to use the old method which is:

jQuery( elem ).data( "events" );

You can do it by crawling the events (as of jQuery 1.8+), like this:

$.each($._data($("#id")[0], "events"), function(i, event) {
  // i is the event type, like "click"
  $.each(event, function(j, h) {
    // h.handler is the function being called
  });
});

Here's an example you can play with:

$(function() {
  $("#el").click(function(){ alert("click"); });
  $("#el").mouseover(function(){ alert("mouseover"); });

  $.each($._data($("#el")[0], "events"), function(i, event) {
    output(i);
    $.each(event, function(j, h) {
        output("- " + h.handler);
    });
  });
});

function output(text) {
    $("#output").html(function(i, h) {
        return h + text + "<br />";
    });
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div id="el">Test</div>
<code>
    <span id="output"></span>
</code>

For jQuery 1.8+, this will no longer work because the internal data is placed in a different object.

The latest unofficial (but works in previous versions as well, at least in 1.7.2) way of doing it now is - $._data(element, "events")

The underscore ("_") is what makes the difference here. Internally, it is calling $.data(element, name, null, true), the last (fourth) parameter is an internal one ("pvt").

Shameless plug, but you can use findHandlerJS

To use it you just have to include findHandlersJS (or just copy&paste the raw javascript code to chrome's console window) and specify the event type and a jquery selector for the elements you are interested in.

For your example you could quickly find the event handlers you mentioned by doing

findEventHandlers("click", "#el")
findEventHandlers("mouseover", "#el")

This is what gets returned:

• element
  The actual element where the event handler was registered in
• events
  Array with information about the jquery event handlers for the event type that we are interested in (e.g. click, change, etc)
  • handler
    Actual event handler method that you can see by right clicking it and selecting Show function definition
  • selector
    The selector provided for delegated events. It will be empty for direct events.
  • targets
    List with the elements that this event handler targets. For example, for a delegated event handler that is registered in the document object and targets all buttons in a page, this property will list all buttons in the page. You can hover them and see them highlighted in chrome.

You can try it here

I use eventbug plugin to firebug for this purpose.