Today i checked my site for errors and i got this in Firebug console:
TypeError: $(...).live is not a function
for this code
$('#payment-address select[name=\'customer_group_id\']').live('change', function() {
......... SOME PHP CODE ....
});
I've read this and the solution is to use on().
But the problem is that i don't know javascript/jquery.
Can anybody help me?
The syntax for .on() is:
.on( events [, selector ] [, data ], handler(eventObject) )
So you can do:
$('body').on('change', "#payment-address select[name=\'customer_group_id\']" , function() {
......... SOME PHP CODE ....
});
use .on()
Syntax
$( elements ).on( events, selector, data, handler );
$(document).on('change', "#payment-address select[name=\'customer_group_id\']" , function() {
//code here
});
$('parentElementPresesntAtDOMready').on('click',"#payment-address select[name=\'customer_group_id\']",function(){
// code here
});
try this:
$('#payment-address').on('change',"select[name=\'customer_group_id\']" function() {
//code here
});
$('#payment-address').on('change', 'select[name=\'customer_group_id\']', function() {
......... SOME PHP CODE ....
})
This is called event delegation. In this way the event is handled by payment-address (as all events bubble up in the DOM tree), and when payment-address handles the event, it checks the origin agains the supplied selector. So you can have different callbacks with different selectors.
Usually the events are attached in this way to the body, as the body always exists and all events eventually bubble to the body
In order to change to on, you need to be aware of how it works.
An event bubbles up through the DOM tree. If you click on a anchor, the event is also passed to the direct parent, to the parents parent, that parent, etc. This will go al the way up to the document
The other answers have given you the method how to replace them, but I miss this:
You can control how far you let it bubble up:
$('#wrapper_of_item').on('click', '.item', function);
This will stop the bubbling up beyond #wrapper_of_item, thus saving some resources.
For the sake of completing the answer, the most basic conversion to on() would be this
// From
$('.elem1').live('click', someFunction);
$('.elem2').live('click', someFunction);
// To:
$(document).ready(function(){
// Direct conversion:
$('.elem1').on('click', someFunction);
$('.elem2').on('click', someFunction);
// Or a bit better:
$('#item1s_closest_wrapper_with_id').on('click', '.elem1', someFunction);
$('#item2s_closest_wrapper_with_id').on('click', '.elem2', someFunction);
});
Related
This question already has answers here:
Event binding on dynamically created elements?
(23 answers)
Closed 5 years ago.
<html>
<head>
<script type="text/javascript" src="jquery.js"></script>
<script type="text/javascript">
$(document).ready(function() {
$("button").click(function() {
$("h2").html("<p class='test'>click me</p>")
});
$(".test").click(function(){
alert();
});
});
</script>
</head>
<body>
<h2></h2>
<button>generate new element</button>
</body>
</html>
I was trying to generate a new tag with class name test in the <h2> by clicking the button. I also defined a click event associated with test. But the event doesn't work.
Can anyone help?
The click() binding you're using is called a "direct" binding which will only attach the handler to elements that already exist. It won't get bound to elements created in the future. To do that, you'll have to create a "delegated" binding by using on().
Delegated events have the advantage that they can process events from descendant elements that are added to the document at a later time.
Source
Here's what you're looking for:
var counter = 0;
$("button").click(function() {
$("h2").append("<p class='test'>click me " + (++counter) + "</p>")
});
// With on():
$("h2").on("click", "p.test", function(){
alert($(this).text());
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
<h2></h2>
<button>generate new element</button>
The above works for those using jQuery version 1.7+. If you're using an older version, refer to the previous answer below.
Previous Answer:
Try using live():
$("button").click(function(){
$("h2").html("<p class='test'>click me</p>")
});
$(".test").live('click', function(){
alert('you clicked me!');
});
Worked for me. Tried it with jsFiddle.
Or there's a new-fangled way of doing it with delegate():
$("h2").delegate("p", "click", function(){
alert('you clicked me again!');
});
An updated jsFiddle.
Use the .on() method with delegated events
$('#staticParent').on('click', '.dynamicElement', function() {
// Do something on an existent or future .dynamicElement
});
The .on() method allows you to delegate any desired event handler to:
current elements or future elements added to the DOM at a later time.
P.S: Don't use .live()! From jQuery 1.7+ the .live() method is deprecated.
Reason:
In jQuery, Click() event Direct binding which attaches the event handler to the element only if the particular element(Html code) exists on the page(after page loads).
Dynamic elements are created with the help of javascript or jquery(not in Html).
It won't consider the future elements(Dynamic) which are created after the page gets loaded.
So the normal click event won't fire on the dynamic element.
Solution :
To overcome this, we should use on() function. on() can delegate the event for both the current and future elements.
Delegated events have the advantage that can attach the handler to the elements which are being added to the document in the future.
Note : delegate(),live() and on() functions have the advantages over the DOM elements. As of JQuery 1.7 delegate() and live() are deprecated(Don't use these).
on() only Can delegate the event for both current and future elements.
So, Your code should be like this
Remove the code from $(document).ready:
$(".test").click(function(){
alert();
});
Change into:
$(document).on('click','.test',function(){
alert('Clicked');
});
Add this function in your js file.
It will work on every browser
$(function() {
$(document).on("click", '#mydiv', function() {
alert("You have just clicked on ");
});
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id='mydiv'>Div</div>
Change
$(".test").click(function(){
To
$(".test").live('click', function(){
LIVE DEMO
jQuery .live()
You need to use .live for this to work:
$(".test").live("click", function(){
alert();
});
or if you're using jquery 1.7+ use .on:
$(".test").on("click", "p", function(){
alert();
});
Try .live() or .delegate()
http://api.jquery.com/live/
http://api.jquery.com/delegate/
Your .test element was added after the .click() method, so it didn't have the event attached to it. Live and Delegate give that event trigger to parent elements which check their children, so anything added afterwards still works. I think Live will check the entire document body, while Delegate can be given to an element, so Delegate is more efficient.
More info:
http://www.alfajango.com/blog/the-difference-between-jquerys-bind-live-and-delegate/
I found two solutions at the jQuery's documentation:
First: Use delegate on Body or Document
E.g:
$("body").delegate('.test', 'click', function(){
...
alert('test');
});
Why?
Answer: Attach a handler to one or more events for all elements that match the selector, now or in the future, based on a specific set of root elements.
link: http://api.jquery.com/delegate/
Second: Put the your function at the "$( document )", using "on" and attach it to the element that you want to trigger this.
The first parameter is the "event handler", the second: the element and the third: the function.
E.g:
$( document ).on( 'click', '.test', function () {
...
alert('test');
});
Why?
Answer: 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 ...
link: https://api.jquery.com/on/
Best way to apply event on dynamically generated content by using delegation.
$(document).on("eventname","selector",function(){
// code goes here
});
so your code is like this now
$(document).on("click",".test",function(){
// code goes here
});
$(.surrounding_div_class).on( 'click', '.test', function () {
alert( 'WORKS!' );
});
Will only work if the DIV with the class .surrounding_div_class is the immediate parent to the object .test
If there is another object in the div that will be filled it wont work.
The problem you have is that you're attempting to bind the "test" class to the event before there is anything with a "test" class in the DOM. Although it may seem like this is all dynamic, what is really happening is JQuery makes a pass over the DOM and wires up the click event when the ready() function fired, which happens before you created the "Click Me" in your button event.
By adding the "test" Click event to the "button" click handler it will wire it up after the correct element exists in the DOM.
<script type="text/javascript">
$(document).ready(function(){
$("button").click(function(){
$("h2").html("<p class='test'>click me</p>")
$(".test").click(function(){
alert()
});
});
});
</script>
Using live() (as others have pointed out) is another way to do this but I felt it was also a good idea to point out the minor error in your JS code. What you wrote wasn't wrong, it just needed to be correctly scoped. Grasping how the DOM and JS works is one of the tricky things for many traditional developers to wrap their head around.
live() is a cleaner way to handle this and in most cases is the correct way to go. It essentially is watching the DOM and re-wiring things whenever the elements within it change.
An alternate and more succinct alternative (IMHO) is to use a raw javascript function that responds to an on click event, then pass the target element back to jQuery if you like. The advantage of this approach is that you can dynamically add your element anywhere, and the click handler will 'just work', and you need not concern yourself with delegating control to parent elements, and so on.
Step 1: Update the dynamic html to fire an onclick event. Be sure to pass the 'event' object as an argument
$("button").click(function() {
$("h2").html("<p class='test' onclick='test(event)'> click me </p>")
});
Step 2: Create the test function to respond to the click event
function test(e){
alert();
});
Optional Step 3: Given you are using jQuery I'm assuming it will be useful to get a reference back to the source button
function test(e){
alert();
// Get a reference to the button
// An explanation of this line is available here
var target = (e.target)? e.target : e.srcElement;
// Pass the button reference to jQuery to do jQuery magic
var $btn = $(target);
});
.live function works great.
It is for Dynamically added elements to the stage.
$('#selectAllAssetTypes').live('click', function(event){
alert("BUTTON CLICKED");
$('.assetTypeCheckBox').attr('checked', true);
});
Cheers,
Ankit.
The Jquery .on works ok but I had some problems with the rendering implementing some of the solutions above. My problem using the .on is that somehow it was rendering the events differently than the .hover method.
Just fyi for anyone else that may also have the problem. I solved my problem by re-registering the hover event for the dynamically added item:
re-register the hover event because hover doesn't work for dynamically created items.
so every time i create the new/dynamic item i add the hover code again. works perfectly
$('#someID div:last').hover(
function() {
//...
},
function() {
//...
}
);
I'm working with tables adding new elements dynamically to them, and when using on(), the only way of making it works for me is using a non-dynamic parent as:
<table id="myTable">
<tr>
<td></td> // Dynamically created
<td></td> // Dynamically created
<td></td> // Dynamically created
</tr>
</table>
<input id="myButton" type="button" value="Push me!">
<script>
$('#myButton').click(function() {
$('#myTable tr').append('<td></td>');
});
$('#myTable').on('click', 'td', function() {
// Your amazing code here!
});
</script>
This is really useful because, to remove events bound with on(), you can use off(), and to use events once, you can use one().
I couldn't get live or delegate to work on a div in a lightbox (tinybox).
I used setTimeout successfullly, in the following simple way:
$('#displayContact').click(function() {
TINY.box.show({html:'<form><textarea id="contactText"></textarea><div id="contactSubmit">Submit</div></form>', close:true});
setTimeout(setContactClick, 1000);
})
function setContactClick() {
$('#contactSubmit').click(function() {
alert($('#contactText').val());
})
}
Also you can use onclick="do_something(this)"inside element
If you have a dinamically added link to some container or the body:
var newLink= $("<a></a>", {
"id": "approve-ctrl",
"href": "#approve",
"class": "status-ctrl",
"data-attributes": "DATA"
}).html("Its ok").appendTo(document.body);
you can take its raw javascript element and add an event listener to it, like the click:
newLink.get(0).addEventListener("click", doActionFunction);
No matter how many times you add this new link instance you can use it as if you where using a jquery click function.
function doActionFunction(e) {
e.preventDefault();
e.stopPropagation();
alert($(this).html());
}
So you will receive a message saying
Its ok
It has better performance than other alternatives.
Extra: You could gain better performance avoiding jquery and using plain javascript. If you are using IE up to version 8 you should use this polyfill to use the method addEventListener
if (typeof Element.prototype.addEventListener === 'undefined') {
Element.prototype.addEventListener = function (e, callback) {
e = 'on' + e;
return this.attachEvent(e, callback);
};
}
You CAN add on click to dynamically created elements. Example below. Using a When to make sure its done. In my example, i'm grabbing a div with the class expand, adding a "click to see more" span, then using that span to hide/show the original div.
$.when($(".expand").before("<span class='clickActivate'>Click to see more</span>")).then(function(){
$(".clickActivate").click(function(){
$(this).next().toggle();
})
});
Use 'on' as click gets bind to the elements already present.
For e.g
$('test').on('click',function(){
alert('Test');
})
This will help.
This question already has answers here:
Event binding on dynamically created elements?
(23 answers)
Closed 5 years ago.
<html>
<head>
<script type="text/javascript" src="jquery.js"></script>
<script type="text/javascript">
$(document).ready(function() {
$("button").click(function() {
$("h2").html("<p class='test'>click me</p>")
});
$(".test").click(function(){
alert();
});
});
</script>
</head>
<body>
<h2></h2>
<button>generate new element</button>
</body>
</html>
I was trying to generate a new tag with class name test in the <h2> by clicking the button. I also defined a click event associated with test. But the event doesn't work.
Can anyone help?
The click() binding you're using is called a "direct" binding which will only attach the handler to elements that already exist. It won't get bound to elements created in the future. To do that, you'll have to create a "delegated" binding by using on().
Delegated events have the advantage that they can process events from descendant elements that are added to the document at a later time.
Source
Here's what you're looking for:
var counter = 0;
$("button").click(function() {
$("h2").append("<p class='test'>click me " + (++counter) + "</p>")
});
// With on():
$("h2").on("click", "p.test", function(){
alert($(this).text());
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
<h2></h2>
<button>generate new element</button>
The above works for those using jQuery version 1.7+. If you're using an older version, refer to the previous answer below.
Previous Answer:
Try using live():
$("button").click(function(){
$("h2").html("<p class='test'>click me</p>")
});
$(".test").live('click', function(){
alert('you clicked me!');
});
Worked for me. Tried it with jsFiddle.
Or there's a new-fangled way of doing it with delegate():
$("h2").delegate("p", "click", function(){
alert('you clicked me again!');
});
An updated jsFiddle.
Use the .on() method with delegated events
$('#staticParent').on('click', '.dynamicElement', function() {
// Do something on an existent or future .dynamicElement
});
The .on() method allows you to delegate any desired event handler to:
current elements or future elements added to the DOM at a later time.
P.S: Don't use .live()! From jQuery 1.7+ the .live() method is deprecated.
Reason:
In jQuery, Click() event Direct binding which attaches the event handler to the element only if the particular element(Html code) exists on the page(after page loads).
Dynamic elements are created with the help of javascript or jquery(not in Html).
It won't consider the future elements(Dynamic) which are created after the page gets loaded.
So the normal click event won't fire on the dynamic element.
Solution :
To overcome this, we should use on() function. on() can delegate the event for both the current and future elements.
Delegated events have the advantage that can attach the handler to the elements which are being added to the document in the future.
Note : delegate(),live() and on() functions have the advantages over the DOM elements. As of JQuery 1.7 delegate() and live() are deprecated(Don't use these).
on() only Can delegate the event for both current and future elements.
So, Your code should be like this
Remove the code from $(document).ready:
$(".test").click(function(){
alert();
});
Change into:
$(document).on('click','.test',function(){
alert('Clicked');
});
Add this function in your js file.
It will work on every browser
$(function() {
$(document).on("click", '#mydiv', function() {
alert("You have just clicked on ");
});
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id='mydiv'>Div</div>
Change
$(".test").click(function(){
To
$(".test").live('click', function(){
LIVE DEMO
jQuery .live()
You need to use .live for this to work:
$(".test").live("click", function(){
alert();
});
or if you're using jquery 1.7+ use .on:
$(".test").on("click", "p", function(){
alert();
});
Try .live() or .delegate()
http://api.jquery.com/live/
http://api.jquery.com/delegate/
Your .test element was added after the .click() method, so it didn't have the event attached to it. Live and Delegate give that event trigger to parent elements which check their children, so anything added afterwards still works. I think Live will check the entire document body, while Delegate can be given to an element, so Delegate is more efficient.
More info:
http://www.alfajango.com/blog/the-difference-between-jquerys-bind-live-and-delegate/
I found two solutions at the jQuery's documentation:
First: Use delegate on Body or Document
E.g:
$("body").delegate('.test', 'click', function(){
...
alert('test');
});
Why?
Answer: Attach a handler to one or more events for all elements that match the selector, now or in the future, based on a specific set of root elements.
link: http://api.jquery.com/delegate/
Second: Put the your function at the "$( document )", using "on" and attach it to the element that you want to trigger this.
The first parameter is the "event handler", the second: the element and the third: the function.
E.g:
$( document ).on( 'click', '.test', function () {
...
alert('test');
});
Why?
Answer: 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 ...
link: https://api.jquery.com/on/
Best way to apply event on dynamically generated content by using delegation.
$(document).on("eventname","selector",function(){
// code goes here
});
so your code is like this now
$(document).on("click",".test",function(){
// code goes here
});
$(.surrounding_div_class).on( 'click', '.test', function () {
alert( 'WORKS!' );
});
Will only work if the DIV with the class .surrounding_div_class is the immediate parent to the object .test
If there is another object in the div that will be filled it wont work.
The problem you have is that you're attempting to bind the "test" class to the event before there is anything with a "test" class in the DOM. Although it may seem like this is all dynamic, what is really happening is JQuery makes a pass over the DOM and wires up the click event when the ready() function fired, which happens before you created the "Click Me" in your button event.
By adding the "test" Click event to the "button" click handler it will wire it up after the correct element exists in the DOM.
<script type="text/javascript">
$(document).ready(function(){
$("button").click(function(){
$("h2").html("<p class='test'>click me</p>")
$(".test").click(function(){
alert()
});
});
});
</script>
Using live() (as others have pointed out) is another way to do this but I felt it was also a good idea to point out the minor error in your JS code. What you wrote wasn't wrong, it just needed to be correctly scoped. Grasping how the DOM and JS works is one of the tricky things for many traditional developers to wrap their head around.
live() is a cleaner way to handle this and in most cases is the correct way to go. It essentially is watching the DOM and re-wiring things whenever the elements within it change.
An alternate and more succinct alternative (IMHO) is to use a raw javascript function that responds to an on click event, then pass the target element back to jQuery if you like. The advantage of this approach is that you can dynamically add your element anywhere, and the click handler will 'just work', and you need not concern yourself with delegating control to parent elements, and so on.
Step 1: Update the dynamic html to fire an onclick event. Be sure to pass the 'event' object as an argument
$("button").click(function() {
$("h2").html("<p class='test' onclick='test(event)'> click me </p>")
});
Step 2: Create the test function to respond to the click event
function test(e){
alert();
});
Optional Step 3: Given you are using jQuery I'm assuming it will be useful to get a reference back to the source button
function test(e){
alert();
// Get a reference to the button
// An explanation of this line is available here
var target = (e.target)? e.target : e.srcElement;
// Pass the button reference to jQuery to do jQuery magic
var $btn = $(target);
});
.live function works great.
It is for Dynamically added elements to the stage.
$('#selectAllAssetTypes').live('click', function(event){
alert("BUTTON CLICKED");
$('.assetTypeCheckBox').attr('checked', true);
});
Cheers,
Ankit.
The Jquery .on works ok but I had some problems with the rendering implementing some of the solutions above. My problem using the .on is that somehow it was rendering the events differently than the .hover method.
Just fyi for anyone else that may also have the problem. I solved my problem by re-registering the hover event for the dynamically added item:
re-register the hover event because hover doesn't work for dynamically created items.
so every time i create the new/dynamic item i add the hover code again. works perfectly
$('#someID div:last').hover(
function() {
//...
},
function() {
//...
}
);
I'm working with tables adding new elements dynamically to them, and when using on(), the only way of making it works for me is using a non-dynamic parent as:
<table id="myTable">
<tr>
<td></td> // Dynamically created
<td></td> // Dynamically created
<td></td> // Dynamically created
</tr>
</table>
<input id="myButton" type="button" value="Push me!">
<script>
$('#myButton').click(function() {
$('#myTable tr').append('<td></td>');
});
$('#myTable').on('click', 'td', function() {
// Your amazing code here!
});
</script>
This is really useful because, to remove events bound with on(), you can use off(), and to use events once, you can use one().
I couldn't get live or delegate to work on a div in a lightbox (tinybox).
I used setTimeout successfullly, in the following simple way:
$('#displayContact').click(function() {
TINY.box.show({html:'<form><textarea id="contactText"></textarea><div id="contactSubmit">Submit</div></form>', close:true});
setTimeout(setContactClick, 1000);
})
function setContactClick() {
$('#contactSubmit').click(function() {
alert($('#contactText').val());
})
}
Also you can use onclick="do_something(this)"inside element
If you have a dinamically added link to some container or the body:
var newLink= $("<a></a>", {
"id": "approve-ctrl",
"href": "#approve",
"class": "status-ctrl",
"data-attributes": "DATA"
}).html("Its ok").appendTo(document.body);
you can take its raw javascript element and add an event listener to it, like the click:
newLink.get(0).addEventListener("click", doActionFunction);
No matter how many times you add this new link instance you can use it as if you where using a jquery click function.
function doActionFunction(e) {
e.preventDefault();
e.stopPropagation();
alert($(this).html());
}
So you will receive a message saying
Its ok
It has better performance than other alternatives.
Extra: You could gain better performance avoiding jquery and using plain javascript. If you are using IE up to version 8 you should use this polyfill to use the method addEventListener
if (typeof Element.prototype.addEventListener === 'undefined') {
Element.prototype.addEventListener = function (e, callback) {
e = 'on' + e;
return this.attachEvent(e, callback);
};
}
You CAN add on click to dynamically created elements. Example below. Using a When to make sure its done. In my example, i'm grabbing a div with the class expand, adding a "click to see more" span, then using that span to hide/show the original div.
$.when($(".expand").before("<span class='clickActivate'>Click to see more</span>")).then(function(){
$(".clickActivate").click(function(){
$(this).next().toggle();
})
});
Use 'on' as click gets bind to the elements already present.
For e.g
$('test').on('click',function(){
alert('Test');
})
This will help.
So i have some data on a page (a table) which based on some options elsewhere may get ajax reloaded from the server.
This table has buttons in it that can be clicked to make other things happen to the records in the table.
I notice that this ...
http://api.jquery.com/on/
... is the recommended approach for attaching simple event handlers to elements but that only attaches to elements that exist right now, and when I do my ajax load I lose the attached handlers.
So I started using this ... http://api.jquery.com/live/ ... and guess what, jquery team did their usual and deprecated it saying I should be using "on".
These functions behave very differently yet jquery docs say i should be using them interchangably so ...
Can someone explain the "on" equivelent of this and how I can get it to work with elements after an ajax call replacing the elements that hae previously been attached to ...
$("some selector").live('click', function (e) {
// some code code
e.preventDefault();
return false;
});
My understanding is that you would do something like ...
$("some selector").on('click', function (e) {
// some code code
e.preventDefault();
return false;
});
My guess is that I then have to re-run this code after performing my ajax call by putting this in to some sort of "initClicks" function and calling it both on page load and after the ajax call.
This seems to be a bit of a back step to me ... or have i missed something here?
Since the elements are added dynamically, you need to use event delegation to register the event handler
// New way (jQuery 1.7+) - .on(events, selector, handler)
$(document).on('click', 'some selector', function(event) {
// some code code
e.preventDefault();
return false;
});
Also, either use e.preventDefault() or return false, as:
return false = e.preventDefault() + e.stopPropagation()
So, there is no need to use both of them at same time.
When you use .on('click', function (e) {}) function, it works only for existing elements.
To handle click event on all selector elements, even for elements which will be added in future, you can use one of these functions:
$(document).on('click', "some selector", function (e) {
// some code code
e.preventDefault();
return false;
});
or:
$("body").delegate("a", "click", function () {
// your code goes here
});
For more information read article about Understanding Event Delegation
live() is not magic, it cannot see future elements, what it was doing is to attach a listener to the first root element of your page document and checks every bubbled event if it match your target selector, and when it find a match, it executes your function.
this is called event delegation
live() has been deprecated for good reasons, mainly the performance hit caused by using it.
then the jQUery team introduced the delegate() function which gave us a new way to achieve the exact result, but it has addressed the performance hit very cleverly by limiting the scope in which it will listen to bubbled events to the possible nearest parent of your now & future elements.
when they introduced the On() function, they gave you the ability to use it as normal event handler, or as a delegated handler for future elements.
so I believe they did a good job for this, giving us the flexibility to use it as we wish according to the specific scenario.
Code Examples:
using delegate():
$( "#TAGERT_ID" ).delegate( "a", "click", function() { // your code goes here}
using on() (for delegated events)
$( "#TAGERT_ID" ).on( "click", "a", function() { // your code goes here}
both ways are the same, and will handle future clicks on a which will be added in the future inside your TARGET_ID element.
TARGET_ID is an example for using ID for your selector, but you can use whatever selector according to your specific need.
The equivalent of said live is
$(document).on('click', "some selector", function (e) {
// some code code
e.preventDefault();
return false;
});
The on() is a single stop for all event handler formats, the model you used is the same as
$("some selector").click(function (e) {
// some code code
e.preventDefault();
return false;
});
which does work based event delegation.
You can never actually attach event listener to an element which does not exist in DOM yet. What live and on method do is attach listener on a parent which exists right now. live is nothing but an on attached on document itself.
I am using jquery 1.8.3 so trying to change from using .live() to the .on()
Like many others on SO - cant get it worrking - what am i doing wrong? If its so wrong to use .live()
why does it work so consistently well!
( txtbxhost is a textbox NOT added dynamically its already in the DOM )
$('#txtbxhost').live('input', function() {
// works everytime
});
$('#txtbxhost').on('change', 'input', function() {
// fails everytime
});
and
$('#txtbxhost').on('change', '#txtbxhost', function() {
// fails everytime
});
and
$(document).on('change', '#txtbxhost', function() {
// fails everytime
});
i'm out of ideas here ... help ...
You probably want:
$(document).on('input', '#txtbxhost', function() {
// code here
});
Check this fiddle
Also, change works only when you blur - In other words click elsewhere after you change text in the texbox.
So, this should work too
$(document).on('change', '#txtbxhost', function() {
// fails everytime
});
Check the updated fiddle
You need to understand how on() differs in behavior to live().
There are really two main approaches to using on(). If the element you are interested in exists on the page at load, you can consider directly binding the event like this:
$('#txtbxhost').on('input', function () {
// some function
});
This would work in much the same way as change() would.
If the element may not exist at page load then you need to work with delegated events. To do this, you must attach the on() to an element that does exist at page load. This can be document or would typically be the closest ancestor to the element the you are interested in that exists on page load. This delegation works by looking at the event bubbling up the DOM element stack to the element to which you bind on(), you then look for a selector within that element to apply the callback to. This looks like this:
$('#some_static_ancestor').on('input', '#txtbxhost', function () {
// some function
});
$(function(){
$('#txtbxhost').on('input', function() {
// do stuff
});
});
That should do it.
In your case you don't really need to use .on(), it's main purpose is to deal with dynamically created elements.
I really liked the .live method as it was straightforward and essentially not much different than your standard event handler.
Alas, it was deprecated and I'm left with the .on method.
Basically, I'm loading and dynamically loading content that I'll need the same event handler triggered on. Rather than add the event handler twice or however many times. .live was great for this, but .on has replaced it and I just can't seem to get it to work.
check this code:
jQuery('#who_me').live('click', function(){
alert('test123');
return false;
});
should be the same as:
jQuery('#who_me').on('click', function(){
alert('test123');
return false;
});
but when I replace content with the .html method after an ajax call only the live method works.
Can anyone clear this up for me?
You aren't using .on() correctly. This is a better implementation if the #who_me object comes and goes.
jQuery(document.body).on('click', '#who_me', function(){
alert('test123');
return false;
});
The selector you use in the jQuery object for .on() must be an object that is present at the time you install the event handler and never gets removed or recreated and is either the object you want the event installed on or a parent of that object. The selector passed as the 2nd argument to .on() is an optional selector that matches the object you want the event on. If you want .live() type behavior, then you must pass a static parent object in the jQuery object and a selector that matches the actual object you want the event on in the 2nd argument.
Ideally, you put a parent object in the jQuery object that is relatively close to the dynamic object. I've shown document.body just because I know that would work and don't know the rest of your HTML, but you'd rather put it closer to your actual object. If you put too many dynamic event handlers on the document object or on document.body, then event handling can really slow down, particularly if you have complicated selectors or handlers for frequent events like click or mousemove.
For reference, the 100% equivalent to your .live() code is this:
jQuery(document).on('click', '#who_me', function(){
alert('test123');
return false;
});
.live() just installs all its event handlers on the document object, and uses event bubbling to see all the events that happen on other objects in the page. jQuery has deprecated .live() because it's better to NOT install all your live event handlers on the document object (for performance reasons). So, pick a static parent object that is closer to your object.
The context when using .live was document, therefore the selector for .on should be document
$(document).on("click","#who_me",function(){...});
The way you're using on, it's basically a replacement for bind, rather than live. With on, as with live and delegate, you can use event delegation, but you must supply a specific containing element (as was always the case with delegate).
At the simplest level, this can be document. In this case, the handler will function exactly as live would have:
jQuery(document).on('click', '#who_me', function() {
alert('test123');
return false;
});
It would be better, however, to find the closest element to contain the elements that will exist. This gives performance gains.
jQuery('#some_el').on('click', '#who_me', function() {
alert('test123');
return false;
});
jQuery(document).on('click', '#who_me', function(){
alert('test123');
return false;
});
should be the equivalent of jQuery.live('#who_me', function() { // code here });
Nope.
$( '#who_me' ).live( 'click', function () { ... });
is the same as:
$( document ).on( 'click', '#who_me', function () { ... });
However, you usually don't want to bind to much handlers to the document object. Instead you bind to the nearest static ancestor (of #who_me, in this case). So:
$( '#wrapper' ).on( 'click', '#who_me', function () { ... });
where #wrapper is an ancestor of #who_me.
To replace .live() you need one more parameter int he .on() call.
// do not use! - .live(events, handler)
$('#container a').live('click', function(event) {
event.preventDefault();
console.log('item anchor clicked');
});
// new way (jQuery 1.7+) - .on(events, selector, handler)
$('#container').on('click', 'a', function(event) {
event.preventDefault();
console.log('item anchor clicked');
});
Source: http://www.andismith.com/blog/2011/11/on-and-off/