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find element from another jquery element

I'm not able to find element from my another jquery element.
Could you please suggest, what I'm doing wrong here?
I have following JS code and I want to find that from total_panels which div has wcPanelTabActive class.
var total_panels = $el.find('.wcPanelTab'),
active_panel = total_panels.find('.wcPanelTabActive');
Chrome console:

You need to use .filter(). As .filter() reduces the set of already matched elements, whereas .find() gets descendants of the matched element.
active_panel = total_panels.filter('.wcPanelTabActive')

Ajax, filter div by id.

I have problem with filter more identic id in the same page.
document.getElementById(val1).innerHTML=xmlhttp.responseText;
I have three the same <div id="name"></div> on one page. And only first div display content. I try with jQuery and filter... but I dont have progress.

The id selector is something to return one unique element (or none if not found). That's why you shouldn't use multiple ids - it will always return [at most] only one (the first).
Fix that fault by using classes or something.
If you really have to get multiple elements with the same id, you can do by using an attribute selector:
$('[id="name"]').html(xmlhttp.responseText);
// or
[].forEach(document.querySelectorAll('[id="name"]'), function(el) {
el.innerHTML = xmlhttp.responseText;
});

document.getElementById
return only first element that having the specified ID. Id should always be unique.
You can try with other attributes like class and then use
document.getElementsByClassName("myClass")
that will return all the elements of given class.

ids should be unique. You shouldn't have two or more elements on the same page with the same id. You can use class names to identify them, and those can definitely be the same. I don't know your code, but try using document.getElementsByClassName (not supported in IE8), or using jQuery to simplify what you are trying to do: $('.my_class_name').html(xmlhttp.responseText)

How to getElementByID in a specific DIV block (JS or JQUery)

I just wanted a fast/easy/simple way to check for existing ID on a specific element (div in this case)..
Can't seem to find code sample for this..im using jquery but i dont think i need to do jquery on this one, just basic getElement.. but i need to isolate the search inside a div block.. because the id does exist in other elements on the page but i need to know if it exist in a specific area/div.
so instead of just
document.getElementById(target_id);
i need something like:
divName.getElementById(target_id);
or
$("document.divName").getElementById(target_id);
or
$(".divName").document.getElementById(target_id);
Can't seem to find something that works.

IDs are supposed to be unique and no two elements in page should have same id. You may search some element with some class in div with specific ID.
$('#divId .someClass')
or using find()
$('#divId').find('.someClass')
or using context, jQuery( selector [, context ] )
$('.someClass', $('#divId'))

var mySubDiv = myParentDiv.querySelector("#mySubDivId")
is equivalent to
var mySubDiv = document.querySelector("#myParentDivId #mySubDivId");
// don't forget the space : #myParentDiv#mySubDivId won't work
where querySelector and querySelectorAll are very useful functions, enough for me to avoid using jQuery : they accept any css selector
in real life, using the same Id for different DOM elements often happens.

id's should be unique, you can check for element using:
$(".your_parent_div").find("div#some_unique_id");

you can use it for the getElementsByTagName or ClassName, but ID is unique over document. so doesn't need to do that. better to use a special ID.
and in every id define as a element in javascript and you can just write id's name and use it, like this :
ID.style.color = red;

According to my understanding on your question, You have used two id's with same name when u execute, It takes only first ID so you are asking to take id from the specific div, well that is bad type of coding to use two id for same name instead go for class if want to use same name.
solution for your question is -this ->
var someDiv = document.getElementsByClassName("divName");
var someId = someDiv[0].getElementById("target_id");

Getting id then selecting that element - jQuery

I'm often finding myself getting various attributes, such as the id of an element or class, then selecting that element and doing something.
What I do now for example is:
var id = $(this).closest(".item").attr('id');
$('#'+id).hide();
Is using '#' and including the id the best way to do this? is there a way to maybe chain these actions together?
Thank you!

If you also want the id at the end, you can chain them like this:
var id = $(this).closest(".item").hide().attr('id');

If you are then going on to manipulate the elements as you do above, a more flexible way would be:
var item = $(this).closest(".item");
item.hide();

Nothing wrong with that method. You might be able to scrunch it into one line, but why?
var id = $(this).closest(".item").hide().attr('id');

Is there a reason why you can't just do
$(this).closest(".item").hide();
Getting the ID and then performing another jQuery selection is going to be slower than this.

You're selecting the item in order to get the id. All you have to do is hide() it there:
$(this).closest(".item").hide()

Just curious as to whether using $(this).closest(".item") without selecting the .attr("id") would work, then just hiding the found closest element. That would save the last line of code, roll it into one line of code. jQuery commands are chainable, so you should just be able to extend your hide command off the same line of code as the .closest() function will return the desired element.
example:
$(this).closest(".item").hide();

I'm not certain if I've understood you correctly, but are you looking for something like this:
$(this).closest(".item").hide();
Here's an example http://jsfiddle.net/alexkey/UtcKk/

Using jQuery to delete all elements with a given id

I have a form with several spans with id="myid". I'd like to be able to remove all elements with this id from the DOM, and I think jQuery is the best way to do it. I figured out how to use the $.remove() method to remove one instance of this id, by simply doing:
$('#myid').remove()
but of course that only removes the first instance of myid. How do I iterate over ALL instances of myid and remove them all? I thought the jQuery $.each() method might be the way, but I can't figure out the syntax to iterate over all instances of myid and remove them all.
If there's a clean way to do this with regular JS (not using jQuery) I'm open to that too. Maybe the problem is that id's are supposed to be unique (i.e. you're not supposed to have multiple elements with id="myid")?

.remove() should remove all of them. I think the problem is that you're using an ID. There's only supposed to be one HTML element with a particular ID on the page, so jQuery is optimizing and not searching for them all. Use a class instead.

All your elements should have a unique IDs, so there should not be more than one element with #myid
An "id" is a unique identifier. Each time this attribute is used in a document it must have a different value. If you are using this attribute as a hook for style sheets it may be more appropriate to use classes (which group elements) than id (which are used to identify exactly one element).
Neverthless, try this:
$("span[id=myid]").remove();

id of DOM element shout be unique. Use class instead (<span class='myclass'>).
To remove all span with this class:
$('.myclass').remove()

if you want to remove all elements with matching ID parts, for example:
<span id='myID_123'>
<span id='myID_456'>
<span id='myID_789'>
try this:
$("span[id*=myID]").remove();
don't forget the '*' - this will remove them all at once - cheers
Working Demo

The cleanest way to do it is by using html5 selectors api, specifically querySelectorAll().
var contentToRemove = document.querySelectorAll("#myid");
$(contentToRemove).remove();
The querySelectorAll() function returns an array of dom elements matching a specific id. Once you have assigned the returned array to a var, then you can pass it as an argument to jquery remove().

You should be using a class for multiple elements as an id is meant to be only a single element. To answer your question on the .each() syntax though, this is what it would look like:
$('#myID').each(function() {
$(this).remove();
});
Official jQuery documentation here.

As already said, only one element can have a specific ID. Use classes instead. Here is jQuery-free version to remove the nodes:
var form = document.getElementById('your-form-id');
var spans = form.getElementsByTagName('span');
for(var i = spans.length; i--;) {
var span = spans[i];
if(span.className.match(/\btheclass\b/)) {
span.parentNode.removeChild(span);
}
}
getElementsByTagName is the most cross-browser-compatible method that can be used here. getElementsByClassName would be much better, but is not supported by Internet Explorer <= IE 8.
Working Demo