Develop Reference

This jQuery toggleClass behaviour seems strange, am I doing this correctly?

I have a CSS rule for hiding elements with a class="hidden" and I'm using jQuery to toggle this class on and off on whatever ID i click on so I can make elements disappear.
Why does this not work?
$(this).attr('id').toggleClass("hidden");
but this does?
var x = "#" + $(this).attr('id');
$(x).toggleClass("hidden");
I know that the id is being taken correctly on the first example, but it seems that to toggle the class I have to add a "#". I haven't seen any examples of others having to resort to this so I'm wondering what madness I have here.
Many thanks

$(this).attr('id').toggleClass("hidden");
You are chaining events here. $(this).attr('id') already returns you a string. So you are technically doing "someid".toggleClass("hidden") which doesn't makes sense.
In your second example, you are actually selecting the same element again via id and firing your method, which is right

.attr('id') returns a string, not an element.
Let's pretend your element has an ID of myThing. Here's what your code translates to:
// 1
"myThing".toggleClass("hidden");
// 2
var x = "#myThing";
$("#myThing").toggleClass('hidden');
But really, if you're getting the ID from this, there's no reason to extract the ID in the first place. Just use this directly.
$(this).toggleClass('hidden');

You can simply use:
$(this).toggleClass("hidden");
$(this) is the actual element you're working with, so you can use this to directly toggle classes with.
In your examples, $(this).attr('id') is a string, and not an element.
This code works, because you're taking the ID (As a string), and selecting the ID on the webpage.:
//Store the id into a string
var x = "#" + $(this).attr('id');
//Pass the ID back into jQuery, and find the element
$(x).toggleClass("hidden");

Jquery [attribute] Selectors

So I've seen several posts explaining how to use a variable in a value for attribute selection. i.e. (where the JS event refers to the div (making it $(this):
HTML
<div id="item1"></div>
<div id="item1" style="display: none;"></div>
JS
var find = $(this).attr("id")
$('div[id="'+find+'"]').show();
But I would like to know how to use a variable in a jquery selector to find something with a similar string to the value of the variable. i.e. finding an element from the example above but looking for "#item1div", where the event target is still "#item1"
HTML
<div id="item1"></div>
<div id="item1div" style="display: none;"></div>
JS
var find = $(this).attr("id")
$('div[id="'+find+"div"'"]').show(); // incorrect syntax
So my question is: How do I correct the above syntax to include an additional string in the attribute check?
I can't find any reference to the correct syntax for how to add compile a string of the value of a variable and an explicit string then check that as the value for x attribute.
I know I can use [id*="'+find+'"] here because the alternate id contains the same characters as the basic one, but I want to know how to target a specific other id based on the first one. For example if I had #item1, #item1div, and #item1img, how can I use an event on "#item1" to find attribute values equal to "item1div" and/or "item1img"
EDIT: I also just realized I can just use [id|="'+find+'"] if I name the divs accordingly with hyphens, but again doesn't solve ids with different endings (or different strings that come after the hyphen)

$('div[id="'+find+"div"'"]') isn't valid Javascript syntax:
$( // jQuery function
'div[id="' // String
+ find // Add variable
+ "div" // Add String
'"]' // Unexpected string! - Error
One example of valid syntax would be:
$('div[id="'+find+'div"]')
However, since it's an id, you can use the id selector instead:
$('div#'+find+'div')

the question is very unclear, but I assume your question boils down to :
Q:how do you search all the elements where it starts with string x ?
A:To get all the elements starting with "item1" you should use:
$("[id^=item1]")

You should use ID selector like below to find an element by ID,
$('#' + find).show();
To find item1div or the dynamic first part - $('#' + find + 'div')
Note: the incorrect syntax you had mentioned is because of a missing + - It should be
// V-- you missed this
$('div[id="'+find+"div"+'"]').show();

To add the explicit string to the attr value you can write as follows
$('[attr="'+attrVal+'extraString"]')
For evample in case of id of div itemdiv
var item1ID = $('#item1').attr('id'); // item1
$('[id="'+item1ID+'div"]') // valid selector to select #item1div

Is it possible to grab a link by its href if it doesn't have a class or ID?

I'm using someone else's app and want to change the innerHTML in between any < a>< /a> tag that has a certain href. But these links don't have a class or ID associated with them and I can't edit the code to give them classes or ID's. Is there a way to grab a tag by its href in JavaScript? I wanted to do something similar to this:
var theLink = document.getElementByHref("example.com");
Otherwise, if that is not possible, can I loop through all the links in the page and choose the ones that have the certain href and innerHTML I'm looking for?

You can use a DOM3-attribute-selector (jQuery doc) to get all elements that contain a certain text in their href attribute. It would look like
$('a[href*="example.com"]')
However, that might not be what you actually want - not only urls to that domain might contain this string. You might do something like begins-with:
$('a[href^="http://example.com"]')
but to get an exact and possibly more complex match, you don't get around a custom filter:
$('a[href]').filter( function() {
return this.hostname == "example.com";
// or check other properties of the anchor element
})

Select all elements that have the example.com value in href attribute:
Live Demo: http://jsfiddle.net/NTGQz/
$('a[href*="example.com"]');
You can also try this, just to be more specific and following the OP "ideal" answer:
Live Demo: http://jsfiddle.net/ksZhZ/
jQuery.fn.getElementsByHref = function(str){ return $('a[href*="' + str + '"]'); };
$(document).ready(function(){
elems = $(this).getElementsByHref('example.com');
});

jQuery has a lot of selectors. The one you want here is the attribute selector.
$('a[href="example.com"')

You can use an attribute selector:
$('a[href="http://example.com"]')

With JQuery attribute selector, you can do this :
$('a[href="example.com"]')

Try this
$('a[href*="example.com"]');
This will select the link that has example.com in the href attribute..

$('a[href="http:google.com"]')

you can do it with jquery: http://api.jquery.com/attribute-equals-selector/
ex: linksToGoogle = $('a[href="http://google.com"]');

You can do this without jQuery.
var links = document.querySelectorAll('a[href*="example.com"]');

You can do this natively with querySelectorAll if your users are on IE8+ or any other browser. This method returns an NodeList of matching elements.
document.querySelectorAll('a[href="exact/value.html"]'); // exact match
document.querySelectorAll('a[href*="partial/value.html"]'); // partial match
document.querySelectorAll('a[href^="starts/with"]'); // href starts with
document.querySelectorAll('a[href$=".html"]'); // href ends with

Search through document and find all inputs with titles

I want to search through my document, and find all inputs with title attribute, but at the same the title attribute can not be empty. So it should look for every input with title attribute that has at least one character in length.
Then I would like to make some event on those inputs (like add them some CSS class).
Is that even possible with jQuery or other javascript library?

I believe this would give you what you want:
$('input[title][title!=""]')
To apply css
$('input[title][title!=""]').addClass('class1 class2 class3');
http://jsfiddle.net/5hkAG/

$("input[title]").not('[title=""]')

var myInputs = [];
$("input").each(function() {
if($(this).attr("title").length > 0) {
myInputs.push(this);
// do other events as usual, using $(this) as selector for current input
}
});
// do something with myInputs, which is an array of all inputs with a title attribute

How to dynamic select element with JQuery by id

I need to dynamic select element with JQuery, I get in code id of element. How to do that ?
I've tried:
var sel='\'#'+id+'\'';
var elem+$(sel);
but it doesn't work ( id is string id of element).

You would use code such as
var ID = 'whatEver';
$('#' + ID).action();
You would then be able to use that to select whatever element you are after.

You don't need the extra quotes. Just:
var elem = $("#"+id);

A live example:: to find text area with attribute data-comment-id with any value
var value = "anyValue";
$('textarea[data-comment-id='+value+']')