Develop Reference

jQuery .attr Not Working Properly, Miss-Retrieving Links

This is a page I'm currently working on as a project
$(function() {
$(".modal-launcher, #modal-background").click(function() {
$(".modal-content, #modal-background").toggleClass("active");
$(".vid-1i").attr("src", "link1");
$(".vid-2i").attr("src", "link2");
$(".vid-3i").attr("src", "link3");
$(".vid-4i").attr("src", "link4");
$(".vid-5i").attr("src", "link5");
$(".vid-6i").attr("src", "link6");
$(".vid-7i").attr("src", "link7");
$(".vid-8i").attr("src", "link8");
//$('html').toggleClass('active').css('top', -(document.documentElement.scrollTop) + 'px');//
});
});
above the actual links are replaced just to display a quick idea of the bad jQuery.
In it, I am attempting to create my own popup launcher for videos; however, I am having trouble using jQuery to replace the "" src of an iframe element to a YouTube link. I am unable to figure out why the jQuery is not working. I understand that the jQuery is, of course, working properly, and that it is me who has written the code incorrectly, but here I am asking if anyone is able to figure out what it is I've done wrong, or what can be changed to make it work.
For some reason, the last video in the jQuery list is always the one retrieved.
Understand that the images are missing from the page due to them being local files and not network locations. Clicking above the captions that read like "Match One" will have the "intended" result, regardless if the image is showing or not.

Coming back to this and understanding more of JavaScript and jQuery, my problem was simply misunderstanding the code. In order to do something like this, one function per link would be more suitable.
function video1()
{
$("#popup, #modal-background").toggleClass("active");
$("#popup").prop("src", "https://www.youtube.com/embed/7h1s15n74r3all1nk");
document.getElementById('scroll').style.cssText ='overflow:hidden';
}
complementary html would look like this:
<div onclick="video1()"></div>
The previous code would run each line, effectively setting the last link as the source of the element. The new code is button independent, ensuring only one link belongs to each button.

Image gallery pagination

I have created the following image gallery.
http://jsfiddle.net/sfiddle/Nf7yR/7/
I think the thing is, that even though I can get a hand on the paragraphs css, the currentIndex won't update, i.e. an event listener seems to be missing.
var thumb = document.getElementById("thumb");
myParagraphs = thumb.getElementsByTagName("p");
console.log(myParagraphs[1]);
function thumby(){
$(myParagraphs[currentIndex]).css("background-color", "red");
}
thumby();
The thing is that I can not manage to link the image index with the index of the pagination dot (which has a normal p tag).
I want to code it in that way that if the first picture is displayed the first dot is red, if the second image is displayed the second ...
How could I approach this?
Thanks for any good advice as I invested a few hours already but can not get my head around it.
PS: no, I want no plugin or ready made imagegallery, I want my approach to work :-)

You made a function thumby() but you are calling it only once (during script start). You just need to call it when you change currentIndex. Here you have fixed code: http://jsfiddle.net/Nf7yR/10/ (I commented my edits).
BTW your code looks terrible. You should indent it properly to make it easier to read :)

Removing data attributes from HTML using jQuery

Can't seem to get this one to work...
I have a page that hides certain links. When the DOM is loaded, I'm using jQuery to toggle some of those elements. This is driven by using a data attribute like so:
<div class="d_btn" data-usr='48'>
<div class="hidden_button">
Then, I have the code:
$.each($(".d_btn"), function() {
var btn = $(this).data('usr');
if ( btn == '48' ){
$(this).children('.hidden_button').toggle();
}
The above all works as planned. The problem is that I am trying to remove the data-usr from the class .d_btn once the if statement is evaluated. I've tried the following and nothing works (i.e., after the page is loaded, the source still shows the data-usr attribute:
$(this).removeAttr("data-usr");
$(this).removeData("usr");
I've been working on this for a couple of hours now and...nothing! Help is greatly appreciated!
UPDATE
I've tried the great suggestions of setting the data attribute to an empty string but I'm still not getting the desired result.
To explain a little further, The reason I'm trying to remove the attribute is so when an ajax response adds another item to the page, the previously added items would already have the button either shown or hidden. Upon AJAX response, I'm calling the same function once the DOM is loaded.
Currently, when something is added via AJAX, it toggles all the buttons (showing the ones that were hidden and vice versa.) Ugh...
I'm also fully willing to try alternatives to my approach. Thanks!
UPDATE
Well, the light bulb just flashed and I am able to do what I want to do by just using .show() instead of .toggle()
Anyway, I'd still like to find an answer to this question because the page will be potentially checking hundreds of items whenever something is added - this seems horribly inefficient (even for a computer, hahaha.)

Why don't you set the value to a random value or empty variable instead if removeAttr does not work..
$(this).attr("data-usr" , '');
$(this).prop("data-usr" , '');

Changing the DOM doesn't affect the source. It affects the DOM, which you can view with the Inspector/Developer Tools. Right click => View Source will give you the original source of the page, not the actual current source as modified by JavaScript.

Set it to a blank string:
$(this).attr("data-usr", "");
I second what Kolink said: check the DOM, not the source. (Chrome: Ctrl + Shift + i).

As others have stated. Checking the source will only show the original unedited source for the webpage. What you need to do is check the DOM using developer tools.
I've just checked everything in Chrome's inspector on jsfiddle here and the attribute is definitely being removed as well as the data.

Javascript getElementById - reading works, altering doesn't

So, I have this pretty complex ajax thing going.
It loads new html (including div tags and all) to show up on the page.
I included a 'more' link to load additional data.
This more link links to my javascript function. The 'more' link is located in a div, which I gave a unique id. The next time the load function is called, I use document.getElementById(the id).style.display="none"; to "remove" this div from the look of the page.
I set error traps for this, the div with that id is found without problems, but javascript fails to change my style property.
I tested alert(document.getElementById(the id).innerHTML); and that worked without problems - hence the title of the question.
So, does anyone have any ideas/do I need to offer more information? The main problem is that it doesn't throw any errors anywhere, yet it fails to complete the task I asked...
Here's a bit of code to go with it -
try
{
var myidthing = "morelink" + ContentStart.toString(); //the id is correct
var div = document.getElementById(myidthing);
if (!div)
{
}
else
{
div.style.display="none"; //this doesn't work, but doesn't raise an error
alert(div.innerHTML); //this works without problem
}
}
catch(theerr)
{
alert(theerr);
}
------------------------->EDIT<-------------------------
I'm incredibly sorry if I upset any people.
I'm also angry at myself, for it was a stupid thing in my code. Basically, I had a variable that stored the contents of a parent div. Then I (succesfully) removed the div using the removeChild() method. Then my code pasted the contents of that vaiable (including the div I wanted gone) back into the parent div.
I switched around the order and it works fine now.
Again, excuse me for this.

Throwing out a few ideas of things to look for:
You said the div is generated by javascript. Is it possible the div you are targeting is not the one you think you are? It could be you are targeting another div, which is already hidden, or obstructed... or maybe the innerHTML you are displaying goes with a different element than the one you intend to target. Put an alert or script breakpoint in the if(!div) case, also, and see if it's going down that path.
If the above code is only a stripped-down version of your actual code, check your actual code for typos (for example: style.display = "none;";)
Using the FireBug plugin for FireFox, inspect the target element after the operation completes, and make sure that the display: none appears in the style information. If not, use FireBug's debugger to walk through your javascript, and see if you can figure out why.
Use FireBug to break on all script errors, in case there is another error causing this behavior.

Try empty quotes instead of 'none' and see if that works?:
document.getElementById('element_id').style.display="";
Failing that, don't change the style, just add a class which hides the element.

Removing appended html using jQuery?

Using jquery, I currently append html to a div on a click event. The following code allows me to fade in only the appended portion of the div:
var html = "..";
$('<div></div>').appendTo("#id").hide().append(html).fadeIn('slow');
This portion works perfectly. But how can I later remove (fade out) only the appended portion? I tried hacking this by storing the html prior to the appending, and then simply hiding everything and showing the stored html. But this does not work well when the same procedure is reused for several divs on the same page (and this seems like poor implementation). Is there a good way to do this?
Just to give an idea of why I need this: Think of a blog type page where for every article on the page there are several comments with only x amount showing by default: the click event fetches the remaining comments and displays them, and then toggling the button again removes the appended comments and sends it back to the original state.

empty() is always an option
jQuery('#main').empty();

Give a look at the empty() function.
It might better solve the problem. Here's the link http://api.jquery.com/empty/

I'd just set and clear the html with '.html()' ...
-- edit
to be more clear, have an area layed out specifically for the addition of these comments:
<div id='commentarea1'></div>
etc.

Try:
var html = "..";
$('<div></div>').appendTo("#id").hide().append(html).fadeIn('slow').addClass('appended');
then later
$('#id .appended').fadeOut('slow'); // or whatever you want to do.

It is not that clear from the question but say you show 5 comments by default and then show x more comments. To get back to the original 5 comment default state you can remove all comments with an index greater than 4 (zero based).
The following assumes each comment goes inside its own div that has a class comment.
$('#id>div.comment:gt(4)').remove();