I am clearly missing something fundamental when it es to jQuery, anonymous functions, and delays.

The following code works only ONCE per page load (it will add the class, then remove it after 1 second, and if i click again, it will add the class, but will NEVER remove the class for the duration of the page, unless I reload the page):

var jElement = $(currElem);
jElement.addClass("highlight")
.delay(1000)
.queue(function(){
$(this).removeClass("highlight");
});

HOWEVER,

if I add the (non-existant) function call as a parameter, AND I call it in my anonymous function, then the add/remove class bination will work indefinitely.

var jElement = $(currElem);
jElement.addClass("highlight")
.delay(1000)
.queue(function(randomFunction){
$(this).removeClass("highlight");
randomFunction(); //this makes it seemingly 'miraculously' work??
});

Side Note:

var jElement = $(currElem);
jElement.addClass("highlight")
.delay(1000)
.queue(function(randomFunction){
$(this).removeClass("highlight");
// this does NOT work; if I dont actually call the 'randomFunction'
// so that function, even though it does nothing; must somehow cause 
// the implicit call of 'dequeue()' ??
});

I am clearly missing something fundamental when it es to jQuery, anonymous functions, and delays.

The following code works only ONCE per page load (it will add the class, then remove it after 1 second, and if i click again, it will add the class, but will NEVER remove the class for the duration of the page, unless I reload the page):

var jElement = $(currElem);
jElement.addClass("highlight")
.delay(1000)
.queue(function(){
$(this).removeClass("highlight");
});

HOWEVER,

if I add the (non-existant) function call as a parameter, AND I call it in my anonymous function, then the add/remove class bination will work indefinitely.

var jElement = $(currElem);
jElement.addClass("highlight")
.delay(1000)
.queue(function(randomFunction){
$(this).removeClass("highlight");
randomFunction(); //this makes it seemingly 'miraculously' work??
});

Side Note:

var jElement = $(currElem);
jElement.addClass("highlight")
.delay(1000)
.queue(function(randomFunction){
$(this).removeClass("highlight");
// this does NOT work; if I dont actually call the 'randomFunction'
// so that function, even though it does nothing; must somehow cause 
// the implicit call of 'dequeue()' ??
});

• javascript
• jquery
• anonymous-function

• Please tell us what exactly you are trying to achieve with the above code. – Venemo Commented Feb 14, 2013 at 20:48
• I was trying to mimic a "temporary highlight" for any input field that did not contain valid information. [For a form validation script]. I noticed thought that my exact code works, regardless of whether the function I pass in is named 'next' or not. Can someone explain this behavior? Its not enough to just pass in a function, you must also call it inside the anonymous function. I could see how function overloading may cause this implicit 'dequeue()' behavior, but the trigger itself exists INSIDE the anonymous function. – Stevers Commented Feb 14, 2013 at 21:11

2 Answers 2

There is no miracle there. This behavior it's written in the documentation of .queue().

Note that when adding a function with .queue(), we should ensure that .dequeue() is eventually called so that the next function in line executes.

$('#foo').slideUp().queue(function() {
  alert('Animation plete.');
  $(this).dequeue();
});

As of jQuery 1.4, the function that's called is passed another function as the first argument. When called, this automatically dequeues the next item and keeps the queue moving. We use it as follows:

$("#test").queue(function(next) {
    // Do some stuff...
    next();
});

the randomFunction is actually referred to as next and references the .dequeue method. Calling it causes the queue to continue on to the next item in the queue.

http://api.jquery./queue/