Develop Reference

trying to attach a click event to an id that only fires once

UPDATE turns out the code is actually working see my answer below
I'm having some troubles here. I thought I found my answer in the .one method, but apparently, .one means ONLY ONCE PER PAGE PER ANYTHING EVER which isn't exactly what I was going for. Here's what my intention was:
$("#someID").one('mouseover', function() {
//do some stuff
});
$("#someOtherID").one('mouseover', function() {
//do some stuff
});
My expectation was that once that first one fired, that mouseover event would no longer fire for THAT ELEMENT.
The problem with this is that once the first one fires, the second one will not fire either. So the .one method appears to be disabling ALL mouseover events for ALL elements after that first one fires.
I did not expect this, I expected the .one to only apply to that first element. Is this just a flaw in my understanding of the .one method or am I coding wrong?
If it's just a flaw in my understanding, could someone point me in the right direction to correct my code?
Thank you in advance!

This is embarassing, I hope I don't get dinged for this and blocked again from stackoverflow (the easiest thing ever to get blocked from and the hardest to get unblocked).
First, #CertainPerformance, thanks for taking the time to look at my question. My real code didn't have the two mistakes you mentioned, I updated my post to reflect the correct syntax.
I'll be honest, my code is working now, and I have no idea why. I suspect I've been dealing with some crazy caching issues which frustrates me because I'm using inMotionHosting which has really great reviews, and I have caching disabled in cPanel.
If anything, maybe this thread will benefit somebody searching "how to make event fire only once in javascript".

You could make the callback run once like this:
// Extend the function prototype
Function.prototype.once = function() {
// Variables
var func = this, // Current function
result;
// Returns the function
return function() {
// If function is set
if(func) {
// Executes the function
result = func.apply(this, arguments);
// Unset the function, so it will not be called again
func = null;
}
// (:
return result;
};
};
// Bind the event to the function you will use as a callback
$("#someID").on('mouseover', function() {
console.log('just once');
}.once());

How to attach an event listener to a javascript var

I am a somewhat green programmer, and quite new to javascript/jquery, but I thought I understood javascript events. Apparently not. I am not able to get event listeners to work as I'd like.
Given javascript:
var Thing = {
//stuff
update: function() {
$.event.trigger({type:'stateUpdate', more:stuff});
}
};
var Room = {
//more stuff
updateHandler: function (e) {
//handle event here
}
};
If I do jquery:
$(document).on('stateUpdate', $Room.updateHandler);
then it works fine, but I can't do either
$(Room).on('stateUpdate', $Room.updateHandler);
or
Room.addEventListerner('stateUpdate', $Room.updateHandler);
The first does nothing, the second gives .addEventListerner is not a function error.
I've googled for hours and can't figure it out. I found something that said .addEventListener only works on objects that implement EventListener, something about handleEvent, and something about functions automatically implementing EventListener. Nothing on how to make an object implement it. Is there no way to add listeners to javascript objects that aren't functions? Am I going to have to create an event handler object, or use 'document' or 'window' and have it call handlers? That seems really ugly.
Should the objects be functions in the first place? Would that work? It seems the current opinion is that making everything functions is just trying to make javascript into something it isn't.

AFAIK there are no way to add a event listener to the plain object, as it is not placed inside DOM. Events are firing inside DOM, and bubbling so your event listener for custom object won't receive it.
There is a http://www.bobjs.com/ framework that can help you implement custom events.

In response to #Barmar (sort of) I believe I worked this out. Confirmation on if this is a a good alternative or not would be nice, though. Basically, I have to do a subscriber thing, right? Almost event/listener, but not quite.
var thing = {
callbacks: {},
regCallback: function (key, which) {
callbacks[key] = which;
},
remCallback: function (key) {
callbacks[key].delete;
}
update: function(e) {
for(var i = 0, len = callbacks.length; i < len;i++){
callbacks[i](e);
};
}
};
var Room = {
updateHandler: function () {
//handle stuff
},
subscribe: function (which, callback) {
which.regCallback('room', callback);
}
unsub: function (which) {
which.remCallback('room');
}
};
//wherever/whenever I need to get updates something like
Room.subscribe(thing, Room.updateHandler);
//unsub
Room.unsub(thing);

Second error is caused by typo: addEventListerner has extra r in it.

jQuery: How can I perform an action after .css has executed?

So my issue is pretty straight forward, since there is seemingly no callback for after a .css is executed, what options do I have for making performing something after a task is done?
I'm creating a simple lightbox, and I need to wait for the center align to finish...
$("#img_lightbox").css("top", top);
So when that completes, I then need to fade in the whole thing, but since there is no callback option (to the best of my knowledge) it will occasionally start fading in before the alignment finishes... how can this prevented?
Any help is appreciated, thank you.

Anything being chained with your jQuery object will execute after the function before it. The easiest way to accomplish what you are asking is with Plugins.
jQuery.fn.myPlugin = function () {
//code to execute
return this;
}
$("#img_lightbox").css("top", top).myPlugin();
You could even write a plugin to execute a custom function, so you do not need to create plugins for every function you might happen to need to run:
jQuery.fn.myCallback= function (callback) {
this.each(function () {
callback.call($(this));
});
return this;
}
$("#img_lightbox").css("top", top).myCallback(function () {
// some code to run where this = $("#img_lightbox")
});
But incase I am still misunderstanding, you may be wanting a callback for your fade function: (otherwise please clarify more)
$("#img_lightbox").fadeIn('slow', function () {
$(this).css("top", top)
});

Adding and removing CSS styles are synchronous functions -- there is no callback because the next statement will be executed once the style has been applied. Rendering of the updated style is slightly different, since that will happen during the next repaint, but unless you're doing some serious number-crunching in your UI code, the difference would be completely unnoticeable. In any case, it would be applied before the 'fading in' starts to happen.
If you're seeing something wrong with your display, I'd suggest that the problem lies elsewhere.

jQuery provides you with a way to tell once the document is "ready" and in the correct state to execute code correctly. Use one of the following:
$(document).ready(function(){
//your code here
});
or the shorter,
$(function(){
//your code here
});
More information at http://api.jquery.com/ready/

jsTree, hover_node, event

The jsTree hover_node callback doesn't return the original ('mouseenter') event.
I'd like to get the mouse position (Client.Y) from the event.
Any suggestions, which don't involve hacking the core?
thanks,
BBZ

After going through the documentation I thought about writting a plugin.
$.jstree.plugin('custom-plugin', {
_fn: {
hover_node: function () {
console.log(arguments);
this.__call_old();
}
}
});
This could be a start (for future reference).
But the argument passed was a node not the event.
Finally I thought of binding to the mouseenter.jstree event.
Which gives me the original event.

Run function only if event default is/isn't prevented

Is there a way to run a function only if event.preventDefault() is called on an event (by another unknown function). This is for a jQuery plugin, so I don't have any knowledge of what other parts of the page might be doing. I've tried this:
Event.test = Event.preventDefault;
Event.preventDefault = function () {
alert('Success');
this.test();
}
but it doesn't work... just behaves as normal, with no errors.
Conversely, I want the opposite too... to call a function only if event.preventDefault() isn't called. In effect, to add a function to the default action for an event. Any ideas? Is all this at all possible?
Edit: Based on the comment, I've got a solution to the first problem: http://jsfiddle.net/nathan/VAePB/9/. It works in Chrome (alerts function preventDefault() { [native code] }, but IE alerts undefined. So IE won't let me define Event.prototype.test, but it will let me redefine Event.prototype.preventDefault. Weird. I'm sure I can come up with a solution to the the second problem based on this one if I can just get it to work in IE.

I'm not sure I've understand. Can't you just use event.isDefaultPrevented() like this

For the first problem, try something like this:
oldPreventDefault = Event.prototype.preventDefault;
Event.prototype.preventDefault = function() {
//do stuff
oldPreventDefault.call(this);
}
I don't know if that will work, but it might be worth a shot.
For the second problem, I would try something similar to live event handling. Put a listener on a parent element (i.e. body or a top-level div). If you can get your hook into preventDefault as noted before, you can use that to set a flag. If the event bubbles up to that element and your flag isn't set, do your extended behavior. Though this won't work with all events, since not all events bubble. Another way to tackle this problem might be to delay execution until the current stack has finished using setTimeout(0,...) and then checking the flag.