[javascript] jQuery when element becomes visible

Basically, I am wondering if there is a way to automatically run a function when an element becomes hidden or visible, not on a user click but automatically in another script.

I don't want this to just run one time, because the elements (such as a slider) constantly change from visible to hidden.

Would this be something that jQuery can do with bind? Such as binding the element's visibility to a function (I don't know how to write this)

If you need me to elaborate more on what I'm trying to do, let me know. Thanks

Pseudocode:

$('#element').bind('display:none', function);
function(){
    //do something when element is display:none
}

$('#element').bind('display:block', function2);
function2(){
    //do opposite of function
}

A catch-all jQuery custom event based on an extension of it's core methods like it was proposed by different people in this thread:

(function() {
    var ev = new $.Event('event.css.jquery'),
        css = $.fn.css,
        show = $.fn.show,
        hide = $.fn.hide;

    // extends css()
    $.fn.css = function() {
        css.apply(this, arguments);
        $(this).trigger(ev);
    };

    // extends show()
    $.fn.show = function() {
        show.apply(this, arguments);
        $(this).trigger(ev);
    };

    // extends hide()
    $.fn.hide = function() {
        hide.apply(this, arguments);
        $(this).trigger(ev);
    };
})();

An external library then, uses sth like $('selector').css('property', value).

As we don't want to alter the library's code but we DO want to extend it's behavior we do sth like:

$('#element').on('event.css.jquery', function(e) {
    // ...more code here...
});

Example: user clicks on a panel that is built by a library. The library shows/hides elements based on user interaction. We want to add a sensor that shows that sth has been hidden/shown because of that interaction and should be called after the library's function.

Another example: jsfiddle.

I like plugin https://github.com/hazzik/livequery It works without timers!

Simple usage

$('.some:visible').livequery( function(){ ... } );

But you need to fix a mistake. Replace line

$jQlq.registerPlugin('append', 'prepend', 'after', 'before', 'wrap', 'attr', 'removeAttr', 'addClass', 'removeClass', 'toggleClass', 'empty', 'remove', 'html', 'prop', 'removeProp');

to

$jQlq.registerPlugin('show', 'append', 'prepend', 'after', 'before', 'wrap', 'attr', 'removeAttr', 'addClass', 'removeClass', 'toggleClass', 'empty', 'remove', 'html', 'prop', 'removeProp');

(function() {
    var ev = new $.Event('display'),
        orig = $.fn.css;
    $.fn.css = function() {
        orig.apply(this, arguments);
        $(this).trigger(ev);
    }
})();

$('#element').bind('display', function(e) {
    alert("display has changed to :" + $(this).attr('style') );
});

$('#element').css("display", "none")// i change the style in this line !!
$('#element').css("display", "block")// i change the style in this line !!

http://fiddle.jshell.net/prollygeek/gM8J2/3/

changes will be alerted.

I just Improved ProllyGeek`s answer

Someone may find it useful. you can access displayChanged(event, state) event when .show(), .hide() or .toggle() is called on element

(function() {
  var eventDisplay = new $.Event('displayChanged'),
    origShow = $.fn.show,
    origHide = $.fn.hide;
  //
  $.fn.show = function() {
    origShow.apply(this, arguments);
    $(this).trigger(eventDisplay,['show']);
  };
  //
  $.fn.hide = function() {
    origHide.apply(this, arguments);
    $(this).trigger(eventDisplay,['hide']);
  };
  //
})();

$('#header').on('displayChanged', function(e,state) {
      console.log(state);
});

$('#header').toggle(); // .show() .hide() supported

Tried this on firefox, works http://jsfiddle.net/Tm26Q/1/

$(function(){
 /** Just to mimic a blinking box on the page**/
  setInterval(function(){$("div#box").hide();},2001);
  setInterval(function(){$("div#box").show();},1000);
 /**/
});

$("div#box").on("DOMAttrModified",
function(){if($(this).is(":visible"))console.log("visible");});

UPDATE

Currently the Mutation Events (like DOMAttrModified used in the solution) are replaced by MutationObserver, You can use that to detect DOM node changes like in the above case.