jQuery Multiple Event Handlers - How to Cancel?

Question

I have two functions bound to a click event at two different times (using jQuery). The order in which they are fired is significant. They are firing in the correct order. The problem is, when the first function returns false, the second function is still firing!

How can I properly cancel the event?

Example code:

$(document).click(function() { 
  alert('a');
  return false;
});

$(document).click(function() {
  alert('b');
});

You will still see the "b" alert message when clicking the page. This is unacceptable!

Answer 1

Use the stopImmediatePropagation function of the jQuery event object.

Keeps the rest of the handlers from being executed. This method also stops the bubbling by calling event.stopPropagation().

$(document).click(function(event) { 
  alert('a');
  event.stopImmediatePropagation();
  return false;
});

$(document).click(function() {
  alert('b');
});

Answer 2

The first thing I'm asking is: why do you have two functions bound to the same click event? Having access to the code, why don't you just make that one single call?

$(function (){
    var callbackOne = function(e){
        alert("I'm the first callback... Warning, I might return false!");
        return false;
    };

    var callbackTwo = function(e){
        alert("I'm the second callback");
    };

    $(document).click(function (e){
        if(callbackOne(e)){
            callbackTwo(e);
        }
    });
});

Answer 3

Thanks, unbind works for redefining functions.

  $(document).ready(function(){
        $("#buscar_mercaderia").click(function(){ alert('Seleccione Tipo de mercaderia'); 
   });
$(".tipo").live('click',function(){
            if($(this).attr('checked')!=''){
                if($(this).val()=='libro'){
                    $("#buscar_mercaderia").unbind('click');
                    $("#buscar_mercaderia").click(function(){  window.open('buscar_libro.php','Buscar Libros', 'width=800,height=500'); });
                }else if($(this).val()=='otra'){
                    $("#buscar_mercaderia").unbind('click');
                    $("#buscar_mercaderia").click(function(){ window.open('buscar_mercaderia.php','Buscar Mercaderias', 'width=800,height=500');  });
                }
            }
        })

Answer 4

Does using unbind help?

$(document).click(function() { 
  alert('a');
  $(this).unbind('click');
  return false;
});

Answer 5

If what nickf said doesn't work, you could use a small state machine:

var trigger = 0;

$(document).click(function() { 

  alert('a');
  if(you_want_to_return_false) {
    trigger = 1;
    return false;
  }
});

$(document).click(function() {
  if(trigger !== 0) {
  alert('b');
  } 
  trigger = 0;
});

Not the prettiest solution, but it will work.

Answer 6

An other solution is to debounce or throttle the function.

This way you could ensure despite it firing multiple times, it only executes within a set duration. This would allow your code to work as-is.