Develop Reference

How to get concrete element by jquery selector?

I want to do something like:
if($(this).hasClass("playButton"))
{
$(this).find("li").removeClass("active");
}
But instead of "this" in "if" statement I want to use any class selector. But I don't know how to get concrete DOM element, which corresponds to the condition.
So I need:
if($(.anyClass).hasClass("playButton"))
{
$(current element, which corresponds to
if condition).find("li").removeClass("active");
}

$(".playButton li").removeClass("active");
...?

You can select the elements using the ".anyClass" selector and then iterate through them using each. In the callback function of each, this will refer to the current DOM element.
$(".anyClass").each(function() {
if ($(this).hasClass("playButton")) {
$(this).find(".btn").removeClass("playButton");
}
});
However, for this particular scenario, you can reach your goal without using each. Simply target the element directly and manipulate it, as #Derek朕會功夫 suggested in his answer.
$(".playButton li").removeClass("active");

Select a div insinde another div with jQuery

So I try to select a div within another div. My html goes like this:
<div id="Stage_game_page1"><div id="cube0">[...]</div><div id="cube1">[...]</div></div>
I want to select my #cube0 within my Stage_game_page specifically, with jQuery or JS.
The goal of the selection is to use it in an loop.
I tried :
var count =$("#Stage_game_page").children().length;
for(i=0; i<count;i++){
$("#Stage_game_page")$("#cube"+i)[...]
}
I don't understand what I'm doing wrong.

var count =$("#Stage_game_page").children().length;
for(i=0; i<count;i++){
$("#cube"+i);
}
This is sufficient to select the "#cube0"/"#cube1"/"#cube2" etc. especially since ids are always unique. To answer the question $("#cube0", "#Stage_game_page")... that is how you select a div in another div

The id attribute should only be used once! I see above that you're using id="cube0" twice. If you want your divs to be recognized in multiple instances, use a class instead (the . instead of the #). Using the same id twice will probably break your script.
I believe for your html, you could use id "cube0", "cube1", etc., as long as you're ok with entering them manually. That should work for the loop you'd like to use.

Loops through each div that starts with the id cube inside Stage_game_page1
$("#Stage_game_page1 > div[id^='cube']").each(function () {
alert($(this).html());
});
JSFiddle
Child Selctor
Starts with Selector

use each() for loop.
$('#Stage_game_page1').children().each(function(index) {
// your code here with index starts from 0
});
or this using jquery attribute starts with selector
$('#Stage_game_page1').find('[id^="cube"]').each(function(index) {
// your code here
});

You need to use .find() or .children() or the like.

The correct jQuery usage would be
$("#Stage_game_page").find('#cube'+i)
to find a div with that id inside the container #stage_game_page

You have duplicate cube0 in your html code..
and i think the look should contain something like that:
$("#cube"+i)[...]

One another solution is:
$("#Stage_game_page1 div[id='cube0']")

Im forcing to use getElementsByClassName()[] rather than getElementByClass()

I have 8 divs with id="div1","div2","div3".... and a class=divs. I also have a button with class="div1","div2","div3"......
When I click the button with id="div1", it will first remove all the class="selected" to all div that has a class="divs" then only the div with id="div1" will have the class selected. And so on.....
I want to use document.getElementByClass() for removing class but it don't work in my FIDDLE. :(
Instead, Im forced to use document.getElementsByClassName()[]. But it seems so hard to code since it requires me to put the specific arrays for the classname.
This is exactly I want to achieve FIDDLE

There is no getElementByClass for a reason: unlike id, class is not specified to be unique in a document. Which element would you get? No, you need the ability to get all of them. And if you get an array, that's solved by looping, not by repeating rows for each index:
However, your design is inefficient; and if you're already using jQuery, you can write it very tightly. This would be better:
<button class="divbuttons" data-div="div1">div1</button>
<button class="divbuttons" data-div="div2">div2</button>
...
then you can:
$(document).ready(function(){
$('.divbuttons').click(function() {
var div = $(this).data("div");
$('.divs.selected').removeClass('selected');
$('#' + div).addClass('selected');
});
});

This is an easy one. There is no document.getElementByClass
You have document.getElementById or document.getElementByClassName

There's no such thing as getElementByClass() because multiple elements can have the same class. There's getElementById() (elements have unique ids, or at least they're supposed to) and getElementsByClassName(), which returns an array of all elements that match the class specified.

try
$(document).ready(function () {
$("button[class^=div]").click(function () {
$(".divs.selected").removeClass("selected");
$("#" + $(this).attr("class")).addClass("selected");
});
});
DEMO

Show each first element in a list of parent elements (jQuery+CSS)

I'm a bit stuck here. I'm trying to show the first div for each section I have using jQuery. There's multiple parent elements .each-business-content-extra which has a few child elements .each. Each .each is set to display none via the CMS, but I want the first .each in each .each-business-content-extra that exists to be set to display:block.
I tried this —
$('.each-business-content-extra .each:first').each(function() {
$(this).show();
});
Any ideas?
Thanks,
R

You can use .eq() to target the first element of each .each class. http://api.jquery.com/eq/
Try this:
$('.each-business-content-extra .each:eq(0)').each(function() {
$(this).show();
});
Alternatively, try this:
$('.each-business-content-extra .each:eq(0)').css('display', 'block');

You can do it your way, but the correct selector is :first-of-type:
$('.each-business-content-extra .each:first-of-type').each(function() {
$(this).show();
});

You can try with this simple one,
$('.each-business-content-extra .each:first-child').show();

Try
$('.each-business-content-extra').find('.each:first').show()
Demo: Fiddle

try this:
$('.each-business-content-extra').children(":first").show();

Turns out it was a combination of everyones...
$('.each-business-content-extra').each(function() {
$(this).find('.each:first').show();
});
Thanks so much.

Get the parent HTML element of certain type with JS

My code looks like this, in closeup:
<h2>
<span class="stuff">[<a id="someid">stuff</a>]</span> <span class="moreStuff">Another test</span>
</h2>
I've found a way to select my a element, and attach an id to it. What I need to do now is select its parent <h2> element, but not the <span> element. How can I do that (JQuery allowed)?
Edit: when I retrieve the selected <a>s, I get an array of them (there's lots of these structures on my page). When I try to write myArray[someIndex].closest("h2"), it says that the element does not have a closest() method. How would I go about this?

One ways is to use the .parents() method of jQuery, with a selector. Something like this.
$("#someid").parents("h2");
Update:
You can use the .closest() method with a selector, to only get the closest parent that match the selector.
$("#someid").closest("h2");
Update 2:
It would be a bit more work to do it with plain JavaScript. Not sure if it is the most efficient, but one way would be to select the element with document.getElementById() and then get a reference to its parent through the parentNode property. Then you would have to check if it is an h2 element, and if not, look at that elements parent node, and so on.
You could check the jQuery source and see how they have implemented the closest method.

I just needed the same thing. here a vanilla javascript variant:
function findParent(startElement, tagName) {
let currentElm = startElement;
while (currentElm != document.body) {
if (currentElm.tagName.toLowerCase() == tagName.toLowerCase()) { return currentElm; }
currentElm = currentElm.parentElement;
}
return false;
}

The <h2> is not the parent of the <a> but it is an ancestor, use .closest() to select it
$("#someid").closest("h2");

try use .parent() for get exactly double or more level up the DOM tree.
$("#someid").parent().parent();