Question

Is is possible to pass an object instead of a selector as the first argument for jQuery delegate?

var ancestor = $('ancestor'),
    children = ancestor.find('a');

ancestor.delegate(children, eventType, handler);

Instead of the regular:

ancestor.delegate('a', eventType, handler);

EDIT

Motivation:

var children = $('a[href^="#"]').map($.proxy(function(i, current) {

    var href = $(current).attr('href');

    if(href.length > 1 && givenElement.find(href).length === 1) return $(current);
},
this));

$(document).delegate(children, eventType, handler);

I want to delegate only the anchor elements that are hash linked to any element as a child of a given element. Basically I want to do something you can’t do with just a selector only.

Answer 1

You could always just set up the delegation and then do your predicate inside the event handler:

ancestor.delegate('a[href^="#"]', 'click', function(ev) {
  if (someElement.find($(ev.target).attr('href')).length > 0) {
    // do whatever with ev.target
  }
});

If you wanted to avoid the runtime price of doing that jQuery DOM search inside the handler, you could pre-tag all the “good” tags:

$('a[href^="#"]').each(function() {
  if (someElement.find($(this).attr('href')).length > 0)
    $(this).addClass("special");
});

Then your delegated event handler can just check

  if ($(ev.target).hasClass('special')) {
    // do stuff
  }

which will perform well enough to not be a problem under any circumstances.

The reason you have to start with a selector for “.delegate()” to work is that that’s the way it’s implemented. The event handler always does something like:

  function genericDelegateHandler(ev) {
    if ($(ev.target).is(theSelector)) {
      userHandler.call(this, ev);
    }
  }

Now, clearly it could also try and compare the actual elements in the case that you set up a delegate without a selector, but it just doesn’t.

edit — @DADU (the OP) correctly points out that if you go to the trouble to mark everything with a class name, then you don’t even need a fancy event handler that tests; an ordinary “.delegate()” will do it. 🙂