Best way to remove an event handler in jQuery?

Question

I have an input type="image". This acts like the cell notes in Microsoft Excel. If someone enters a number into the text box that this input-image is paired with, I setup an event handler for the input-image. Then when the user clicks the image, they get a little popup to add some notes to the data.

My problem is that when a user enters a zero into the text box, I need to disable the input-image's event handler. I have tried the following, but to no avail.

$('#myimage').click(function { return false; }); 

Answer 1

jQuery ≥ 1.7

With jQuery 1.7 onward the event API has been updated, .bind()/.unbind() are still available for backwards compatibility, but the preferred method is using the on()/off() functions. The below would now be,

$('#myimage').click(function() { return false; }); // Adds another click event $('#myimage').off('click'); $('#myimage').on('click.mynamespace', function() { /* Do stuff */ }); $('#myimage').off('click.mynamespace'); 

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jQuery < 1.7

In your example code you are simply adding another click event to the image, not overriding the previous one:

$('#myimage').click(function() { return false; }); // Adds another click event 

Both click events will then get fired.

As people have said you can use unbind to remove all click events:

$('#myimage').unbind('click'); 

If you want to add a single event and then remove it (without removing any others that might have been added) then you can use event namespacing:

$('#myimage').bind('click.mynamespace', function() { /* Do stuff */ }); 

and to remove just your event:

$('#myimage').unbind('click.mynamespace'); 

Answer 2

This wasn't available when this question was answered, but you can also use the live() method to enable/disable events.

$('#myimage:not(.disabled)').live('click', myclickevent);  $('#mydisablebutton').click( function () { $('#myimage').addClass('disabled'); }); 

What will happen with this code is that when you click #mydisablebutton, it will add the class disabled to the #myimage element. This will make it so that the selector no longer matches the element and the event will not be fired until the 'disabled' class is removed making the .live() selector valid again.

This has other benefits by adding styling based on that class as well.