Remove jQuery delegated event handler on specific object

问题

I've attached delegated event handlers to a number of elements on the page using a single selector. As the events are triggered for individual elements, I'd like to turn off only that element's event handler based on some conditional logic. That means I won't necessarily want to disable the event on the very first click. But I can't figure out how to do it without turning off all of them.

HTML:

<button>One</button>
<button>Two</button>
<button>Three</button>

JS:

$(document).on('click', 'button', function(ev) {
    // doesn't work because argument needs to be a string
    $(document).off('click', $(ev.target));

    // doesn't do what I want b/c turns off events on all buttons, not just this one
    $(document).off('click', 'button');

    // doesn't work because event is on document, not button
    $(ev.target).off('click');
});

jQuery's off documentation says I need to provide a string as the second argument, not a jQuery object ($(ev.target)), but if I provide a string, there's no value that refers only to the item clicked.

From jQuery's off documentation:

To remove specific delegated event handlers, provide a selector argument. The selector string must exactly match the one passed to .on() when the event handler was attached. To remove all delegated events from an element without removing non-delegated events, use the special value "**".

So how do I turn off a delegated event handler for a specific element?

Here's a JSFiddle of the code above

UPDATE: Added a few examples of options that don't work, based on initial answers provided.

回答1:

After having read thru on the web, the answer is you can't! You can either remove all or none. A workaround could be something like the following.

$(document).on('click', '.btn', function (ev) {
    alert('pressed');
    $(this).removeClass("btn");
});

Demo@Fiddle

Sample HTML:

<button class="btn">One</button>
<button class="btn">Two</button>
<button class="btn">Three</button>

回答2:

Question: Do you have to use the delegated events? LIke LShetty said, it is not possible to remove a delegated event for a single element. You either remove the entire event delegation, or leave it. You could try using a different selector instead like in this example

$('button').on('click', function(ev) {
    $('#output').append('Clicked! ');
    $(this).off('click');
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script>
<button>One</button>
<button>Two</button>
<button>Three</button>
<div id="output"></div>

回答3:

In addition to what lshettyl said (the current top post) - an additional work around is to bind a new event listener directly to the element that you're trying to remove the listener and call stopPropagation() therein.

What this will do is prevent the event from traveling up the DOM and reaching the event handler that is initially bound to the document. Also this will allow you to keep some functionality on the button click, such as an alert to the user that this button has already been clicked - or something to that effect.

$(document).on('click', 'button', function(ev) {
    // Your logic to occur on button click

    // Prevent further click on just this button
    $(this).click(function(event) {
        event.stopPropagation();
    }):
});

来源：https://stackoverflow.com/questions/30512253/remove-jquery-delegated-event-handler-on-specific-object

标签

javascript

jquery

delegates

event-delegation