Jquery ignore elements with "disabled" class - javascript

I'm using jquery and creating event handlers like this:
$('#some_selector a.add').live('click', function(){...});
However, I need to not execute handlers when an element has disabled class. Then I wrote the following to achieve this:
$('#some_selector a.add:not(.disabled)').live('click', function(){...});
But I'm tired of watching over all the places that I need to add :not(.disabled), sometimes I forget to add it and so on. Moreover, if I have an anchor element and my handler prevents default action on it, than adding :not(.disabled) will cause browser to open next page instead of doing nothing.
So is there a way to set up automatic disabling on handler execution when an element meets some condition (like having "disabled" class)?

Here is what you can do:
First, bind an event handler to the .disabled elements which prevents other handlers to be executed and prevents the default action:
$('#some_selector a.add.disabled').live('click', function(event){
event.stopImmediatePropagation();
event.preventDefault();
});
Then you can bind your other event handlers as you did before. As event handlers are executed in the order they have been bound, the event handler for disabled elements will always execute first and prevent other handlers from executing (through stopImmediatePropagation [docs]).
DEMO

You could use <button> instead of <a> for this. A <button> with the disabled attribute set will not respond to clicks at all:
A form control that is disabled must prevent any click events that are queued on the user interaction task source from being dispatched on the element.
For example: http://jsfiddle.net/ambiguous/sCv8n/
You can style a <button> to look pretty much any way you want too.

Related

Need to get info from any element, which was clicked, but not from parent elements

Need to get info from any element, which was clicked.
Example:
<div>text1<section>text2</section></div>
and JS
$(function(){
$('body *').click(function(){
alert($(this).get(0).tagName.toLowerCase());
});
});
If I click text2, parent element throw alert too. I need only first alert from section. How I can block next alerts from all parent elements of section.
Use event.stopPropagation() to prevent the event from firing on the containing elements.
$(function(){
$('body *').click(function(e){
e.stopPropagation();
alert($(this).get(0).tagName.toLowerCase());
});
});
Just wanted to expand on Kooilnc answer - Using on with event delegation is another option.
Event delegation would be nice if you have an event listener bound before or after on a node that needs to listen to a click handler that has bubbled up. If you stopPropagation, this obviously would be an issue.
Here's a fiddle with a demo:
http://jsfiddle.net/ahgtLjbn/
Let's say a buddy of yours has bound an event listener to a node higher up in the DOM tree. He expects any events that bubble up to it, to be handled by his script.
Using event delegation, the event still bubbles up (so your buddies code will still fire), but it will only alert once (since we called e.stopPropagation).
Calling on without event delegation, or binding the event directly using click (which, under the hood, is just calling on) will prevent the event from bubbling, so your buddies code will never run.

change html preventDefault

I have a weird recursive situation.
I am changing some HTML inside a element with a small widget and HTML5 contenteditable.
I binded on that element some events such as:
$('.myelement).on('DOMNodeInserted DOMNodeRemoved DOMCharacterDataModified', ..
Those events trigger some AJAX call that on success also modifies the same element.
$('.myelement').html(new_value)
But the thing is, this also triggers those binded events on the element. And then i get a unstoppable ajax recursion.
Is it possible to do something like
$('.myelement').html(new_value).preventDefault()
as in, don't trigger any of the binded events triggers?
No.
Instead, you can unbind the handlers while you update the element, or set a flag while updating and check for that flag in the handler and do nothing.

jQuery programmatically trigger events

What all events can be triggered programmatically using jQuery? Also is there any important differences to be remembered when one is doing event triggering using jQuery Vs a natural way of it being triggered?
Every event can be programmatically fired, just use the callback-less version of it.
Example:
$('#button').click(function() { alert('event hanlder'); });
$('#button').click(); // generate the event
About your second question, there should be no difference between the native and jQuery event handlers.
One thing that is neat though is that jQuery binds this to the element that received the event, inside the callback (this doesn't happen in native event handlers):
$('#button').click(function() { alert(this); }); // here 'this' == document.getElementById('button');
Warning: the element referenced by this is not "jQuery augmented". If you want to traverse or modify it with jQuery goodness you'll have to do something like var $this = $(this);
You should know the differences between trigger and triggerHandler in jQuery.
trigger
trigger attempts to replicate the natural event as best as it can. The event handler for the event being triggered get's executed, but the default browser actions will not always be replicated exactly. For example $('a#link).trigger('click'); will execute the javascript function bound to the links click event handler, but will not redirect the browser to the href of the anchor, like a normal click would. EX: http://jsfiddle.net/AxFkD/
All the short forms of the trigger call behave exactly like trigger IE. click(), mouseup(), keydown(), etc
triggerHandler
triggerHandler prevents bubbling up ( EX. http://jsfiddle.net/LmqsS/ ), it avoids default browser behaviour and just executes the events callback, and it returns the return value of the event handler instead of a jQUery object for chaining.
You should also be aware that trigger affects all elements matched by a selector, but triggerHandler only affects the first one EX: http://jsfiddle.net/jvnyS/
You can trigger any event programmatically. But most of the events cannot be simulated as the natural event using programmatic triggers.
//to trigger a click event on a button
$("buttonSelector").trigger("click");
First, for obvious reasons, you cannot trigger the ready event.
That said, events raised by trigger() behave the same way as if they were triggered by the user. In particular, the event handlers are called in the same order.
The only difference I know of is that triggered events did not bubble up the DOM tree in older versions of jQuery (that behavior was fixed in version 1.3).

How to call JS to click a table element

Assume I get a table element with ID="emTab", how do I call JS to click it?
Thanks.
document.getElementById("emTab").onclick = function() {
// your code goes here
};
See element.onclick
To trigger click event
document.getElementById("emTab").click();
See element.click
The click method is intended to be
used with INPUT elements of type
button, checkbox, radio, reset or
submit. Gecko does not implement the
click method on other elements that
might be expected to respond to
mouse–clicks such as links (A
elements), nor will it necessarily
fire the click event of other
elements.
Non–Gecko DOMs may behave differently.
When a click is used with elements
that support it (e.g. one of the INPUT
types listed above), it also fires the
element's click event which will
bubble up to elements higher up the
document tree (or event chain) and
fire their click events too. However,
bubbling of a click event will not
cause an A element to initiate
navigation as if a real mouse-click
had been received.
Cross browser way
If you can use jQuery then it would be
$("#emTab").trigger("click");
Firing events cross-browser - http://jehiah.cz/archive/firing-javascript-events-properly
its simple using JQuery
$('#emTab').click(functionToCall);
while in JS
document.getElementById('emTab').onclick = function() {};
for details on DOM events:
http://www.howtocreate.co.uk/tutorials/javascript/domevents

Onclick event override with firebug

I have added an onclick event, which opens a new tab/page, to a button which has an action already (I don't know which action cause it isn't displayed in source, or maybe it's a form submit action).
Button originally also opens a page in new tab, what I want to do is fire up some function after my onclick attribute executes which will stop execution and that default page opening will not happen, only my page will load.
Is there something that can be done?
It sounds like the event is bubbling up after you have handled it. To stop this happening, add event.cancelBubble = true at the end of your handler.
Using jQuery, you can do this:
$('button').click(function() {
//do something
return false; // stop the event from propagating
});
Try getting your function that your call on the onclick event to return false. This will cause any existing action by the button to be overridden
If the handler was set using 'onclick=' you can simply rewrite the onclick property.
If a handler was added to an element with addEventHandler or attachEvent, you can remove it with removeEventHandler or detachEvent, using the same parameters that were used to set it.
If you don't know the setter, or if it used an anonymous function, you can't remove it.
You could replace the element with a duplicate that has no events and set your own on the new element.
(cloneNode is not supposed to clone events, but it sometimes does in some browsers.)

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