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I'm trying to attach events using on() based on changing selectors

I have a button that can be in 2 different states (lets say Lock and Unlock). When I click on the button, I update the class on the button to reflect the binary opposite state. Each class has a different event attachment function using on(string, callback). For some reason the event being triggered remains the first callback assigned based on the original class.
HTML:
<button class="lock">Lock</button>
<button class="unlock">Unlock</button>
JavaScript:
$(document).ready(function() {
$('.lock').on('click', function() {
// Perform some magic here
console.log('Lock!');
$(this).removeClass('lock')
.addClass('unlock')
.html('Unlock');
});
$('.unlock').on('click', function() {
// Perform some magic here
console.log('Unlock!');
$(this).removeClass('unlock')
.addClass('lock')
.html('Lock');
});
});
https://jsfiddle.net/c283uaog/ for testing.
Expected console output when clicking on the same button repeatedly:
Lock!
Unlock!
Lock!
Actual console output:
Lock!
Lock!
Lock!
Any assistance would be greatly desired

use event Delegation
$(document).on('click','.lock', function() {
$(document).on('click','.unlock', function() {
updated Demo
Or use in single function with toggleClass
$(document).on('click', '.lock,.unlock', function () {
$('#output').html($(this).attr('class'));
$(this).toggleClass('lock unlock').text($(this).attr('class'));
});
ToggleClass demo

I'd do it this way, attaching only one event: http://jsfiddle.net/jozu47tv/
$(".lock").on('click', function(e) {
e.preventDefault();
if($(this).hasClass("lock")) {
$(this).removeClass("lock").addClass("unlock");
console.log("lock -> unlock");
} else {
$(this).removeClass("unlock").addClass("lock");
console.log("unlock -> lock");
}
})

Use Event Delegation method, Try this updated fiddle,
$(document).ready(function() {
$(document).on('click', '.lock', function() {
$('#output').html('Lock!');
$(this).removeClass('lock')
.addClass('unlock')
.html('Unlock');
});
$(document).on('click', '.unlock', function() {
$('#output').html('Unlock!');
$(this).removeClass('unlock')
.addClass('lock')
.html('Lock');
});
});

Probably, this question could answer you in a better way:
jQuery .on function for future elements, as .live is deprecated
$(document).on(event, selector, handler)

Change your html to this:
<button class="locker lock" >Lock</button>
<button class="locker unlock"">Unlock</button>
<div id="output">Output</div>
and your Js to this:
$(document).ready(function() {
$('.locker').on('click', function() {
if($(this).hasClass("lock")){
$(this).removeClass("lock");
$(this).addClass("unlock");
$(this).html("unlock");
}
else if($(this).hasClass("unlock")){
$(this).removeClass("unlock");
$(this).addClass("lock");
$(this).html("lock");
}
});
});

Dynamically add event handler to an href which is also dynamically generated

I have a button and when this button is clicked I need to generate a link dynamically and add a handler to it which shows a twitter bootstrap modal. I tried this:
$(function() {
function showModal() {
$("#myModal").modal("show");
}
$(document).on("click", "#my_btn", function() {
//generating a link a adding a handler to it which is "showModal()"
//.....
$("#my_href").html("Some text123 <a href='#' onclick='showModal();'>test123</a>.");
//.....
})
});
But when I clink a this link the error is being thrown saying
Uncaught ReferenceError: showModal is not defined
I can, of course, move showModal() out of $(function() {...}). But I was wondering, is there a better way to do it? And in general, is this a good way to achieve what I want?
UPDATE:
Even after moving showModal() out of $(function() {...}) it doesn't work, it redirects me to the same page but doesn't show pop up.

Don't use inline Javascript. You've posted a perfect example of how you should be doing this right in your question: Use .on on the containing element.
$(document).on("click", "#my_btn", function() {
$("#my_href").html("Some text123 <a href='#'>test123</a>.");
});
$('#my_href').on('click', 'a', showModal);

Use jQuery delegated event handlers to add the click handler
$(function () {
function showModal() {
$("#myModal").modal("show");
}
$(document).on("click", "#my_btn", function () {
//generating a link a adding a handler to it which is "showModal()"
//.....
$("#my_href").html("Some text123 <a href='#' class='showmodal'>test123</a>.");
//.....
});
$("#my_href").on('click', '.showmodal', showModal)
});
In your case you have a inlined event handler which is calling showModal, this expects a method named showModal in the global scope but you have added the method showModal as a closure method in the dom ready handler.

$(function() {
function showModal() {
alert("Modal");
}
$('<a/>',{
href: '#',
text: "Click Me",
click: function(e) {
e.preventDefault();
showModal();
}
}).appendTo('#my_href');
});
jsfiddle

Here you should attach your event to the body or document not to the button
$("body").on( "click","button[id$=my_btn]", function(){
alert( "hi" );
})

html div onclick event

I have one html div on my jsp page, on that i have put one anchor tag, please find code below for that,
<div class="expandable-panel-heading">
<h2>
<a id="ancherComplaint" href="#addComplaint"
onclick="markActiveLink(this);">ABC</a>
</h2>
</div>
js code
$('.expandable-panel-heading:not(#ancherComplaint)').click(function () {
alert('123');
});
function markActiveLink(el) {
alert($(el).attr("id"));
}
here I when I click on div I got alert with 123 message, its fine but when I click on ABC I want message I want to call markActiveLink method.
JSFiddle
what is wrong with my code? please help me out.

The problem was that clicking the anchor still triggered a click in your <div>. That's called "event bubbling".
In fact, there are multiple solutions:
Checking in the DIV click event handler whether the actual target element was the anchor
→ jsFiddle
$('.expandable-panel-heading').click(function (evt) {
if (evt.target.tagName != "A") {
alert('123');
}
// Also possible if conditions:
// - evt.target.id != "ancherComplaint"
// - !$(evt.target).is("#ancherComplaint")
});
$("#ancherComplaint").click(function () {
alert($(this).attr("id"));
});
Stopping the event propagation from the anchor click listener
→ jsFiddle
$("#ancherComplaint").click(function (evt) {
evt.stopPropagation();
alert($(this).attr("id"));
});
As you may have noticed, I have removed the following selector part from my examples:
:not(#ancherComplaint)
This was unnecessary because there is no element with the class .expandable-panel-heading which also have #ancherComplaint as its ID.
I assume that you wanted to suppress the event for the anchor. That cannot work in that manner because both selectors (yours and mine) select the exact same DIV. The selector has no influence on the listener when it is called; it only sets the list of elements to which the listeners should be registered. Since this list is the same in both versions, there exists no difference.

Try this
$('.expandable-panel-heading:not(#ancherComplaint)').click(function () {
alert('123');
});
$('#ancherComplaint').click(function (event) {
alert($(this).attr("id"));
event.stopPropagation()
})
DEMO

Try following :
$('.expandable-panel-heading').click(function (e) {
if(e.target.nodeName == 'A'){
markActiveLink(e.target)
return;
}else{
alert('123');
}
});
function markActiveLink(el) {
alert($(el).attr("id"));
}
Here is the working demo : http://jsfiddle.net/JVrNc/4/

Change your jQuery code with this. It will alert the id of the a.
$('.expandable-panel-heading:not(#ancherComplaint)').click(function () {
markActiveLink();
alert('123');
});
function markActiveLink(el) {
var el = $('a').attr("id")
alert(el);
}
Demo

You need to read up on event bubbling and for sure remove inline event handling if you have jQuery anyway
Test the click on the div and examine the target
Live Demo
$(".expandable-panel-heading").on("click",function (e) {
if (e.target.id =="ancherComplaint") { // or test the tag
e.preventDefault(); // or e.stopPropagation()
markActiveLink(e.target);
}
else alert('123');
});
function markActiveLink(el) {
alert(el.id);
}

I would have used stopPropagation like this:
$('.expandable-panel-heading:not(#ancherComplaint)').click(function () {
alert('123');
});
$('#ancherComplaint').on('click',function(e){
e.stopPropagation();
alert('hiiiiiiiiii');
});

Try out this example, the onclick is still called from your HTML, and event bubbling is stopped.
<div class="expandable-panel-heading">
<h2>
<a id="ancherComplaint" href="#addComplaint" onclick="markActiveLink(this);event.stopPropagation();">ABC</a>
</h2>
</div>
http://jsfiddle.net/NXML7/1/

put your jquery function inside ready function for call click event:
$(document).ready(function() {
$("#ancherComplaint").click(function () {
alert($(this).attr("id"));
});
});

when click on div alert key
$(document).delegate(".searchbtn", "click", function() {
var key=$.trim($('#txtkey').val());
alert(key);
});

jQuery, Triggering event from Class

Please take a look at the following code and fiddle.
CODE
$("#enable").click(function(e) {
if (!$("#enable").data('isOn')) {
$("#holder").find('.clickable').each(function(d) {
$(this).css('border', '1px solid red');
$(this).addClass('clickEnabled');
});
$("#enable").data('isOn', true);
} else {
$("#holder").find('.clickable').each(function(d) {
$(this).css('border', '');
$(this).removeClass('clickEnabled');
});
$("#enable").data('isOn', false);
}
});
$(".clickEnabled").click(function(e) {
alert('clicked');
});
Fiddle: http://jsfiddle.net/qAuwt/
I am basically trying to toggle a "clickEnabled" class on elements when a button is pressed. The toggling is working as the border is changing however the clickEnabled class is not responding to click events

There are no .clickEnabled elements when you set the event handler. You can still catch the click event, though:
$(document).on("click", ".clickEnabled", function(){
alert("Hello, world!");
});​

Change:
$(".clickEnabled").click(function (e) {
alert('clicked');
});
To:
$(".clickable").click(function (e) {
if ( $(this).hasClass("clickEnabled") )
{
alert('clicked');
}
});
As #araxanas mentioned, the .clickEnabled don't exist on load. So I switched the selector to .clickable, which do. However, you only want to handle the click when they're enabled. That's why I've added the conditional. It'll only alert if the clicked element has the clickEnabled class.
Also, it might help to move the css out of javascript, that way you can see visually if the class is there or not, see my updated fiddle.

The problem is that when page loaded, the click event handler binds to no elements (because there is no element with class 'clickEnabled').
The solution is to change the .click() method to .live() method:
$(".clickEnabled").live('click', function (e) {
alert('clicked');
});

How do I bind to the click event from within the click event when I need to do it repeatedly?

I've got code so that when you click on a word, it is replaced by another word.
<script>
$(document).ready(function() {
$('.note_text').click(function(){
$(this).remove();
$('#note_div').append('<span class="note_text">new</span>');
// re-applying behaviour code here
});
});
</script>
<div id="note_div">
<span class="note_text">preparing</span>
</div>
I need the appended word to have the same click behaviour. What is the best way to do this?

change
$('.note_text').click(function(){
to
$('.note_text').live('click',function(){
This will cause anything on your page that ever gets the class 'note_text' to have the behaviour set by .live

You should use a .live()help or .delegate()help binding for that purpose.
$(function() {
$('#note_div').delegate('.note_text', 'click', function(e) {
$(e.target).parent().append("<span class='note_text'>new</span>").end().remove();
});
});
Demo: http://www.jsfiddle.net/PkngP/2/

You could rebind the handler:
function handler(){
$(this).remove();
$('#note_div').append("<span class="note_text">new</span>");
$(".note_text").unbind("click");
$('.note_text').click(handler);
}
$(document).ready(function() {
$('.note_text').click(handler);
});