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jquery not changing src of element

I have a select element in my HTML, i then have an iframe that displays PDFs. i have some jquery code that should change the "src" attribute of the iframe when a user selects an option but so far i cant seem to get it to trigger. when i click an option from the select nothing happens. i have tried using .change() and .on("change") but they do not work. i have console.log within the function but it does not log anything into the console.
The jquery
$(document).ready(function(){
var x = $("#demo-category").val();
$("#demo-category").on("change", "#demo-category", function(){
$("#readframe").attr("src", x);
console.log(x);
console.log("test");
});
});
should you need any more information i will provide it if i can.

Event delegation (that is, your
.on("change", "#demo-category", function(){
) is for when the element that triggers the event is different from the element that the listener is added to. When you want to add a plain listener to a single element, don't pass another selector - if you do that, the listener won't fire. Instead just call .on('change', fn....
Also, you're retrieving x on document load. Retrieve the new value after #demo-category changes instead:
$(document).ready(function() {
$("#demo-category").on("change", function() {
var x = $(this).val();
$("#readframe").attr("src", x);
console.log(x);
console.log("test");
});
});

I think this will work
$(document).ready(function(){
$("#demo-category").on("change", function(){
$("#readframe").attr("src", $(this).val());
});
});

How to get the current/this object on button click using bind event?

I have following code:
$(document).bind('click', '.btn-yes .btn-no', function() {
$(this).toggleClass("btn-warning");
alert("test"); // <-- this works...
});
.btn-yes and .btn-no are two classes which are attached to buttons. When they are clicked, I want the btn-warning class to get attached to that button, but this is not working...
Can anyone let me know what I am doing wrong?

You need to have a comma , between your selector:
'.btn-yes, .btn-no'
and you should use event delegation only if your elements are dynamically generated after page load.
If such a case then the preferred method is .on() as per latest jQuery library. You can see this in action in the snippet below.
$(document).on('click', '.btn-yes, .btn-no', function() {
$(this).toggleClass('btn-warning');
});
.btn-warning{background:red; color:yellow;}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<button class='btn-yes'>Yes</button><button class='btn-no'>No</button>
Problem:
When you don't use comma , in your selector such as in this case you are actually trying to bind a click event on the child .btn-no which has the parent .btn-yes.

Try this:
$(document).bind('click','.btn-yes .btn-no',function(e){
$(e.target).toggleClass("btn-warning");
});

'.btn-yes .btn-no' denotes to the btn-no inside btn-yes not separate elements. So, separate your elements with a comma and use click event for that.
I also recommend you to use on instead of bind method:
$(document).on('click', '.btn-yes, .btn-no', function(){
$(this).toggleClass("btn-warning");
});

If you have jquery version 1.7+ use on method
$(document).on('click', '.btn-yes,.btn-no', function() {
$(this).toggleClass("btn-warning");
});

Cant select ids that I loaded with jQuery

I understand that you need to use ".on" to use code that you loaded with jquery after the page has loaded. (At least I think it works that way)
So I tried that but it somehow just doesn't do a thing at all. No errors in the console either.
$("#forgot_password").click(function(){
var forgot_password = '<div id="toLogin" style="cursor:pointer;">Prijava</div>'
$("#loginPopupForm").html(forgot_password);
});
$("#toLogin").on("click", function(){
alert("Hello");
});
So when I click on #forgot_password it does execute the first click function. But when I click on #toLogin it doesn't do anything and I think its because its loaded with jquery when I click on #forgot_password

Try this
$("#loginPopupForm").on("click", "#toLogin", function(){
alert("Hello");
});

You need to bind to an element that is present when the page loads, like body for example. Just change your code to what is shown below
$("body").on("click", "#forgot_password", function(){
var forgot_password = '<div id="toLogin" style="cursor:pointer;">Prijava</div>'
$("#loginPopupForm").html(forgot_password);
});
$("body").on("click", "#toLogin", function(){
alert("Hello");
});

You are setting the on to the wrong thing. You want it to be:
$(document).on('click', '#toLogin', function() {alert('hello') });
The id isn't there until you do the other click event, so jQuery is not finding any element to set the click event on. You need to have an element that has been rendered in the DOM to set the event on.

You are totally right about the problem : on() targets only elements that are already existing as it runs.
What you need in jQuery is called Delegated event and is well explained on the Jquery doc page.
The difference in the code is thin, but it's how you're supposed to do.

You have to specify the parent element
$("#toLogin").on("click","#loginPopupForm", function(){
alert("Hello");
});
in the 2nd argument of the on

jQuery .on('change', function() {} not triggering for dynamically created inputs

The problem is that I have some dynamically created sets of input tags and I also have a function that is meant to trigger any time an input value is changed.
$('input').on('change', function() {
// Does some stuff and logs the event to the console
});
However the .on('change') is not triggering for any dynamically created inputs, only for items that were present when the page was loaded. Unfortunately this leaves me in a bit of a bind as .on is meant to be the replacement for .live() and .delegate() all of which are wrappers for .bind() :/
Has anyone else had this problem or know of a solution?

You should provide a selector to the on function:
$(document).on('change', 'input', function() {
// Does some stuff and logs the event to the console
});
In that case, it will work as you expected. Also, it is better to specify some element instead of document.
Read this article for better understanding: http://elijahmanor.com/differences-between-jquery-bind-vs-live-vs-delegate-vs-on/

You can use any one of several approaches:
$("#Input_Id").change(function(){ // 1st way
// do your code here
// Use this when your element is already rendered
});
$("#Input_Id").on('change', function(){ // 2nd way
// do your code here
// This will specifically call onChange of your element
});
$("body").on('change', '#Input_Id', function(){ // 3rd way
// do your code here
// It will filter the element "Input_Id" from the "body" and apply "onChange effect" on it
});

Use this
$('body').on('change', '#id', function() {
// Action goes here.
});

Just to clarify some potential confusion.
This only works when an element is present on DOM load:
$("#target").change(function(){
//does some stuff;
});
When an element is dynamically loaded in later you can use:
$(".parent-element").on('change', '#target', function(){
//does some stuff;
});

$("#id").change(function(){
//does some stuff;
});

you can use:
$('body').ready(function(){
$(document).on('change', '#elemID', function(){
// do something
});
});
It works with me.

You can use 'input' event, that occurs when an element gets user input.
$(document).on('input', '#input_id', function() {
// this will fire all possible change actions
});
documentation from w3

$(document).on('change', '#id', aFunc);
function aFunc() {
// code here...
}

I'm having a jQuery onclick issue

So I'm going to explain this with an example.
I have a "like" button (class: .like) for my feed or stream. When the user clicks it ( using $(".like") ), it ajaxes it's way to refreshless insert the like into the database (using jQuery).
When it's inserted, I change the text to "Unlike" and the class to ".unlike".
However, when a user reclicks it, it just goes through the same function again, instead of going to the $(".unline").click function. Do I have to "update" the script or something?
For example:
$(".like").click(function(){
alert("Like!");
$(this).attr("class", "unlike");
});
$(".unlike").click(function(){
alert("Unlike!");
$(this).attr("class", "like");
});
The problem is that it won't to the unlike function, it will just repeat the like function even though the attribute is changed.

That is because the "unlike" attr. hasn't been added to the dom when the script loaded. Try this:
<body>
<div class="like_it_or_not">
HELLO!
</div>
</body>
And the JS
$("body").on('click','.like_it_or_not', function(){
$(this).toggleClass('like', 'unlike');
if ($(this).hasClass('like')) {
alert('like');
} else if ($(this).hasClass('unlike')) {
alert('unlike');
}
});

If you don’t want to delegate your click event (which is over-engineering IMO), do a check in the handler:
$(".like").click(function(){
alert( $(this).hasClass('unlike') ? 'unlike' : 'like' );
$(this).toggleClass("unlike like");
});
http://jsfiddle.net/NScyM/
It should check for the 'unlike' class each time you click and toggle classes as expected.

The event binding occurs when you assign run the above code. You have to rebind the event every time, or, better yet, use event delegation:
$(document)on("click",".like",function(){
alert("Like!");
$(this).addClass("unlike");
$(this).removeClass("like");
});
$(document)on("click",".unlike",function(){
alert("Unike!");
$(this).addClass("like");
$(this).removeClass("unlike");
});

I think you will have to use live() or on() to make this work:
$(".like").live("click", function() {
$(this).removeClass("like").addClass("unlike");
});
$(".unlike").live("click", function() {
$(this).removeClass("unlike").addClass("like");
});

Try this one
$(".like").click(function(){
alert("Like!");
$(this).removeClass("like");
$(this).attr("class", "unlike");
});
$(".unlike").click(function(){
alert("Unlike!");
$(this).removeClass("unlike");
$(this).attr("class", "like");
});

To keep my code clean on stuff like this, I assign a class that never changes and tie the click event to that. The styling classes simply act as CSS changes. For instance:
<button class="vote like">button text</button>
$('.vote').click(function () {
var alertText = ($(this).hasClass('like')) ? 'Like!' : 'Unlike!';
alert(alertText);
$(this).toggleClass('like').toggleClass('unlike');
});

Try this
$(document).on('click', '.like', function(){
alert("Like!");
$(this).html('Unlike').removeClass("like").addClass("unlike");
});
$(document).on('click', '.unlike', function(){
alert("Unlike!");
$(this).html('Like').removeClass("unlike").addClass("like");
});
DEMO.

The unlike click event handler has not been associated with the new item. If you're going to be changing the class dynamically like that you're going to want to look at the (jQuery on handler)[http://api.jquery.com/on/]
$(document).on('click',".like", function(){
alert("Like!");
$(this).addClass("unlike").removeClass('like');
});
$(document).on('click',".unlike",function(){
alert("Unlike!");
$(this).addClass("like").removeClass('unlike');
});