I am a bit confused, I have a bunch of elements that get added via jquery using a ajax call and I want to attach a click handler to them (there could be a lot).
But I have no idea how to even begin this, I looked at .on and it is really confusing. I want to attach a click event handler for a certain class so that when I click on it, I get the this.id and then do stuff with it.
What you're trying to do is called event delegation.
You want to set the event listener on a higher element in the DOM that'll never change, but only fire off the event handler if the child element that has been clicked matches a specific selector.
Here's how it's done with jQuery's .on():
$(document).on('click', '.your-selector', function(){
alert(this.id);
});
P.S. You could probably apply the event listener to an element lower down in the DOM tree...
This will get you the id of a clicked element with the class "test"...
$(".test").on("click", function() {
var id = $(this).attr("id")
});
You'll need to run that after the ajax call returns. It will only bind the click event to elements that exist when it runs, so it's no good at document.ready.
Related
How can i call a function when element is live, i think we just raise a function by raising an event by live..
$('#a').live('click',function(){
//some code
});
but i need a function to be called when element is lived,Any Idea.
The context is
initially i dont have a select box , if i got a particular select box
then i want call a function that pushes result into it..
you can use on delegate event...
$(document).on("click",'#a',function(){
alert(clicked);
});
however,it is always recommended that you use the closest static elements that are in the HTML markup, then $(document) for better performance.. you can read more about on delegate event here..
Event handlers are bound only to the currently selected elements; they must exist on the page at the time your code makes the call to .on(). To ensure the elements are present and can be selected, perform event binding inside a document ready handler for elements that are in the HTML markup on the page
Live is deprecated and removed on jQuery 1.9. Use .on()
This enable click on any element with id #a added after page is loaded
$(document).on('click','#a',function(){
//Code here
});
I have the following code:
var $reviewButton = $('span.review_button');
$reviewButton
.live('click',
function(){
$('#add_reviews').show();
}
)
Later in the script, I use an AJAX call to load some content and another instance of $('span.review_button') enters the picture. I updated my code above to use '.live' because the click event was not working with the AJAX generated review button.
This code works, as the .live(click //) event works on both the static 'span.review_button' and the AJAX generated 'span.review_button'
I see however that .live is depracated so I have tried to follow the jquery documentations instructions by switching to '.on' but when I switch to the code below, I have the same problem I had before switching to '.live' in which the click function works with the original instance of 'span.review_button' but not on the AJAX generated instance:
var $reviewButton = $('span.review_button');
$reviewButton
.on('click',
function(){
$('#add_reviews').show();
}
)
Suggestions?
The correct syntax for event delegation is:
$("body").on("click", "span.review_button", function() {
$("#add_reviews").show();
});
Here instead of body you may use any static parent element of "span.review_button".
Attention! As discussed in the comments, you should use string value as a second argument of on() method in delegated events approach, but not a jQuery object.
This is because you need to use the delegation version of on().
$("#parentElement").on('click', '.child', function(){});
#parentElement must exist in the DOM at the time you bind the event.
The event will bubble up the DOM tree, and once it reaches #parentElement, it is checked for it's origin, and if it matches .child, executes the function.
So, with this in mind, it's best to bind the event to the closest parent element existing in the DOM at time of binding - for best performance.
Set your first selector (in this case, div.content) as the parent container that contains the clicked buttons as well as any DOM that will come in using AJAX. If you have to change the entire page for some reason, it can even be change to "body", but you want to try and make the selector as efficient as possible, so narrow it down to the closest parent DOM element that won't change.
Secondly, you want to apply the click action to span.review_button, so that is reflected in the code below.
// $('div.content') is the content area to watch for changes
// 'click' is the action applied to any found elements
// 'span.review_button' the element to apply the selected action 'click' to. jQuery is expecting this to be a string.
$('div.content').on('click', 'span.review_button', function(){
$('#add_reviews').show();
});
I'm using jQuery's .on() event handler and it's only working when I use $(document).
This works:
$(function() {
$(document).on("click", ".search .remove", function(e) {
console.log("clicked");
});
});
This does not work:
$(function() {
$(".search .remove").on("click", function(e) {
console.log("clicked");
});
});
Nothing happens on that second one...no errors or anything. It just doesn't fire.
You are using two different syntaxes of .on which have two very different outcomes.
Your first is:
$(context).on("event","targetselector",handler)
This binds the event to context, and any events of type event that gets to the context that has an e.target that can be selected with targetselector will trigger the handler with e.target as the context. this is commonly known as event delegation.
Your second syntax is
$(targetselector).on("event",handler)
In this case, the event is bound directly to the elements currently on the page that match targetselector, not future elements. This is essentially the same as the old .bind.
Your second example doesn't work because your elements are created dynamically. When using .on() with dynamically inserted elements, you have to bind it via an element that isn't inserted dynamically, i.e. one that exists on the page at load time.
You can continue to use document as an ancestor element but in terms of performance you might want to find an element closer in the DOM to ".search .remove".
From the jQuery docs on .on():
Event handlers are bound only to the currently selected elements; they
must exist on the page at the time your code makes the call to .on().
To ensure the elements are present and can be selected, perform event
binding inside a document ready handler for elements that are in the
HTML markup on the page. If new HTML is being injected into the page,
select the elements and attach event handlers after the new HTML is
placed into the page. Or, use delegated events to attach an event
handler, as described next.
Delegated events have the advantage that they can process events from
descendant elements that are added to the document at a later time. By
picking an element that is guaranteed to be present at the time the
delegated event handler is attached, you can use delegated events to
avoid the need to frequently attach and remove event handlers. This
element could be the container element of a view in a
Model-View-Controller design, for example, or document if the event
handler wants to monitor all bubbling events in the document. The
document element is available in the head of the document before
loading any other HTML, so it is safe to attach events there without
waiting for the document to be ready.
Your first method is the on() equivalent for the deprecated method live(). Probably your elements get inserted dynamically after the page loading has finished.
You could rewrite your code like following and it should work:
$(function() {
$(".search").on("click", ".remove", function(e) {
console.log("clicked");
});
});
I have two select-boxes, each of them is in span element with specific id. The first select-box is country, the other one is city list. When I select a country the innerHtml of city select-box container span is replaced by response of ajax function everything is good. But I want to fire a function by useing onchange attribute of selectbox if at the begining of page loading addeventListener function works fine but affter replacement of innerHtml of span it does not work and after replacement the id of city selecbox is same es before replacement. I am just using.
document.getElementById('to_city').addEventListener('change',doSomething,false);
this code is initialized by onload of window element.
It works without ajax replacement but dont after.
When you replace contents with AJAX you need to bind event again. so its good idea to bind event again after replacing content.
There is a way to avoid it using event bubbling.
JQuery 1.4+ supports onchange event propagation so you can use jquery delegate function to achieve same. http://api.jquery.com/delegate/
with Jquery only one line do the work.
$("#container").delegate("#to_city", "change", doSomething); // Workd in all browsers
I ignored IE in below example as you are using addEventListener which is not supported by IE.
Without Jquery
Working example (Not working in IE) : http://codebins.com/bin/4ldqpb1/2
document.getElementById("container").addEventListener( 'change', function(e) {
var targ=e.target;
if (targ.id == "to_city") { //you just want to capture to_city event
//DO STUFF FOR SELECT
//DO STUFF
doSomething();
alert("id: " + targ.id + "\nvalue: " + targ.value);
}
}, false)
Explanation:
When you bind any events they are bound to that particular element not the selector or ID. so when you replace the content and new replace element with the new element with the same ID, new element doesnt have any event attached. so you need to attache event again. so if you attach event after AJAX content replace doSomething will work. but that is not a very good solution.
We are using event bubbling concepts. many events are bubbled to the top of the document. (IE doesn't bubble change event)
So we write handler on the container and listen for the event. each event has a target or srcElement which says which dom element firing this event. if the dom element is what we are looking for execute function. in this can we are looking for element with ID to_city that's why if condition.
I am using jQuery v.1.7.1 where the .live() method is apparently deprecated.
The problem I am having is that when dynamically loading html into an element using:
$('#parent').load("http://...");
If I try and add a click event afterwards it does not register the event using either of these methods:
$('#parent').click(function() ...);
or
// according to documentation this should be used instead of .live()
$('#child').on('click', function() ...);
What is the correct way to achieve this functionality? It only seems to work with .live() for me, but I shouldn't be using that method. Note that #child is a dynamically loaded element.
Thanks.
If you want the click handler to work for an element that gets loaded dynamically, then you set the event handler on a parent object (that does not get loaded dynamically) and give it a selector that matches your dynamic object like this:
$('#parent').on("click", "#child", function() {});
The event handler will be attached to the #parent object and anytime a click event bubbles up to it that originated on #child, it will fire your click handler. This is called delegated event handling (the event handling is delegated to a parent object).
It's done this way because you can attach the event to the #parent object even when the #child object does not exist yet, but when it later exists and gets clicked on, the click event will bubble up to the #parent object, it will see that it originated on #child and there is an event handler for a click on #child and fire your event.
Try this:
$('#parent').on('click', '#child', function() {
// Code
});
From the $.on() documentation:
Event handlers are bound only to the currently selected elements; they
must exist on the page at the time your code makes the call to .on().
Your #child element doesn't exist when you call $.on() on it, so the event isn't bound (unlike $.live()). #parent, however, does exist, so binding the event to that is fine.
The second argument in my code above acts as a 'filter' to only trigger if the event bubbled up to #parent from #child.
$(document).on('click', '.selector', function() { /* do stuff */ });
EDIT: I'm providing a bit more information on how this works, because... words.
With this example, you are placing a listener on the entire document.
When you click on any element(s) matching .selector, the event bubbles up to the main document -- so long as there's no other listeners that call event.stopPropagation() method -- which would top the bubbling of an event to parent elements.
Instead of binding to a specific element or set of elements, you are listening for any events coming from elements that match the specified selector. This means you can create one listener, one time, that will automatically match currently existing elements as well as any dynamically added elements.
This is smart for a few reasons, including performance and memory utilization (in large scale applications)
EDIT:
Obviously, the closest parent element you can listen on is better, and you can use any element in place of document as long as the children you want to monitor events for are within that parent element... but that really does not have anything to do with the question.
The equivalent of .live() in 1.7 looks like this:
$(document).on('click', '#child', function() ...);
Basically, watch the document for click events and filter them for #child.
I know it's a little late for an answer, but I've created a polyfill for the .live() method. I've tested it in jQuery 1.11, and it seems to work pretty well. I know that we're supposed to implement the .on() method wherever possible, but in big projects, where it's not possible to convert all .live() calls to the equivalent .on() calls for whatever reason, the following might work:
if(jQuery && !jQuery.fn.live) {
jQuery.fn.live = function(evt, func) {
$('body').on(evt, this.selector, func);
}
}
Just include it after you load jQuery and before you call live().
.on() is for jQuery version 1.7 and above. If you have an older version, use this:
$("#SomeId").live("click",function(){
//do stuff;
});
I used 'live' in my project but one of my friend suggested that i should use 'on' instead of live.
And when i tried to use that i experienced a problem like you had.
On my pages i create buttons table rows and many dom stuff dynamically. but when i use on the magic disappeared.
The other solutions like use it like a child just calls your functions every time on every click.
But i find a way to make it happen again and here is the solution.
Write your code as:
function caller(){
$('.ObjectYouWntToCall').on("click", function() {...magic...});
}
Call caller(); after you create your object in the page like this.
$('<dom class="ObjectYouWntToCall">bla... bla...<dom>').appendTo("#whereeveryouwant");
caller();
By this way your function is called when it is supposed to not every click on the page.