Develop Reference

How to add and remove class dynamically to child div based on value in Jquery

if data value is matching with any div inside requestsampler class then dynamically add new class(sampleClass) to test class inside the matching container
js:
var data = **somevalue**;
data is dynamic value
html:
<div class="requestsampler">
<div class= "**somevalue**">
<div class="test"> // add new class <div class="test sample class">
//
</div>
</div>
<div class= "somevalue2">
<div class="test">
//
</div>
</div>
<div class= "somevalue3">
<div class="test">
//
</div>
</div>
</div>
tried not working:
$('.requestsampler').hasClass(data) {
$(.'requestsampler .`${data}` .test').addClass('sampleclass');
}

You could simply use Attribute Contains Prefix Selector [name|="value"] for more info please refer http://jqapi.com/#p=attribute-contains-prefix-selector.. below is the code for your example.
$(document).ready(()=>{
var data = "somevalue"; $('div[class|="'+data+'"]>.test').addClass("sampleclass");
})
.sampleclass{
background-color:red;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div class="requestsampler">
<div class= "somevalue">
<div class="test"> // add new class <div class="test sample class">
//
</div>
</div>
<div class= "somevalue2">
<div class="test">
//
</div>
</div>
<div class= "somevalue3">
<div class="test">
//
</div>
</div>
</div>

you could try jquery elem.find() api. And also use className with string and numeric combination instead of symbols
i have changed the condition with element find length. Because hasClass() only perform on the selector element. So if you are using find() they will find the matched element.
And also your if condition does not make any sense, without condition is also working same
Updated
If you need first test element. use .eq(0) or else use different className for the first test element
var data = "somevalue";
if ($('.requestsampler').find(`.${data}`).length > 0) {
$('.requestsampler').find(`.${data}`).find('.test').eq(0).addClass('sampleclass');
}
.sampleclass {
background: red;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div class="requestsampler">
<div class="somevalue">
<div class="test"> // add new class
<div class="test sample class">
sample
</div>
</div>
<div class="somevalue2">
<div class="test">
//
</div>
</div>
<div class="somevalue3">
<div class="test">
//
</div>
</div>
</div>

Find the index of a div inside a container

I have a container with multiple divs and in each div I have a handler on which you can click.
The requirement is to return the index of the div in the container for further processing.
I've simplified the code for readability purposes.
The HTML:
<div class="container">
<div class="block">
<div class="handler">
Click
</div>
</div>
<div class="block">
<div class="handler">
Click
</div>
</div>
<div class="block">
<div class="handler">
Click
</div>
</div>
<div class="block">
<div class="handler">
Click
</div>
</div>
</div>
The Javascript code I tried so far but I always get -1 as the index:
$(document).ready(function(){
$('.handler').click(function(e) {
let index = Array.prototype.indexOf.call($('.container'), $(this).parents('.block'));
console.log(index);
});
});
I also created a fiddle.
So what am I doing wrong here?

You can do the following,
$('.handler').click(function(e) {
var el = e.target;
console.log([].indexOf.call(el.parentNode.parentNode.children, el.parentNode));
});
However if you want to know what was wrong in your code,
Array.prototype.indexOf.call($('.container')[0].children, $(this).parents('.block')[0])
This part should fix the problem in your code. You have been doing it all right, but for the parameter of indexOf we needed the children array of .container and clicked element.
You were passing the container element and current clicked element as an array. That is Array.prototype.indexOf.call('[Container Element]', ['current clicked div']) Which is not right. You should pass something like this,
Array.prototype.indexOf.call('[children, children, children...]', 'current clicked div element').
It was happening because the $('.container') returns an array with the element having a class name .container. But we needed all the children array of the element that contains container class.
And $(this).parents('.block') returns an array with the matching elements even if it is only one.

You can access the index using the index method on parent element of selection.
$(document).ready(function(){
$('.handler').click(function(e) {
console.log($(this).parent().index())
});
});

You can do that like this. Find the index of the closest element of the clicked element, which is also a direct child of .handler. To find index, use index().
$(document).ready(function() {
$('.handler').click(function(e) {
let index = $(this).closest('.block').index()
console.log(index);
});
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div class="container">
<div class="block">
<div class="handler">
Click
</div>
</div>
<div class="block">
<div class="handler">
Click
</div>
</div>
<div class="block">
<div class="handler">
Click
</div>
</div>
<div class="block">
<div class="handler">
Click
</div>
</div>
</div>

You're checking at the wrong level of nesting in your HTML. I believe what you're trying to do is check from one level higher, at ".container" and get the index of the ".block" element that was clicked.
This code works in your Fiddle:
$(document).ready(function(){
$('.handler').click(function(e) {
const p = e.target.parentElement.parentElement;
const index = Array.prototype.indexOf.call(p.children, e.target.parentElement);
console.log(p.className) // "container"
console.log(index)
});
});

This can be done simply using delegate in jQuery.
I modify your JSFiddle code.
$(".container").delegate('.block', 'click', function () {
console.log( $(this).index() );
})

u can use a id
<div class="container">
<div class="block">
<div id='0' class="handler">
Click
</div>
</div>
<div class="block">
<div id='1' class="handler">
Click
</div>
</div>
<div class="block">
<div id='2' class="handler">
Click
</div>
</div>
<div class="block">
<div id='3' class="handler">
Click
</div>
</div>
</div>
$(document).ready(function(){
$('.handler').click(function(e) {
let index = this.id
console.log(index);
});
});
https://jsfiddle.net/vhrt596x/2/

HTML JavaScript querySelector to find an element whose child has a specific data attribute

In my below HTML markup, I'd like to query the <div> that has a data-parent set to "true", and the contained child has data-child-gender set to "true" and inner html is "male".
<div id="grandparent">
<div id="parent1" data-parent="true">
<div id="child1" data-child-gender="false">
male
</div>
</div>
<div id="parent2" data-parent="true">
<div id="child2" data-child-gender="true">
female
</div>
</div>
<div id="parent3" data-parent="false">
<div id="child3" data-child-gender="true">
female
</div>
</div>
<div id="parent4" data-parent="true">
<div id="child4" data-child-gender="true">
male
</div>
</div>
</div>
Given the above scenario, the expected <div> is parent4.
What is the JavaScript querySelector to use?

First use querySelectorAll which will give an array. Then iterate over it and check and get element with required data attribute.
After that you can use use a if & check the content inside it
let k = document.querySelectorAll('[ data-parent=true]').forEach(function(item) {
let elem = item.querySelector('[data-child-gender=true]');
if (elem !== null && elem.innerHTML.trim() === 'male') {
console.log(item.id)
}
})
<div id="grandparent">
<div id="parent1" data-parent="true">
<div id="child1" data-child-gender="false">
male
</div>
</div>
<div id="parent2" data-parent="true">
<div id="child2" data-child-gender="true">
female
</div>
</div>
<div id="parent3" data-parent="false">
<div id="child3" data-child-gender="true">
female
</div>
</div>
<div id="parent4" data-parent="true">
<div id="child4" data-child-gender="true">
male
</div>
</div>
</div>

There isn't one querySelector you can use for this (as you can't use it to select specific text within elements). However, you can use .querySelector() with .filter() to get more specific results:
const true_children = [...document.querySelectorAll("[data-parent='true'] [data-child-gender='true']")];
const res = true_children.filter(({innerHTML:g}) => g.trim() === "male");
console.log(res);
<div id="grandparent">
<div id="parent1" data-parent="true">
<div id="child1" data-child-gender="false">
male
</div>
</div>
<div id="parent2" data-parent="true">
<div id="child2" data-child-gender="true">
female
</div>
</div>
<div id="parent3" data-parent="false">
<div id="child3" data-child-gender="true">
female
</div>
</div>
<div id="parent4" data-parent="true">
<div id="child4" data-child-gender="true">
male
</div>
</div>
</div>

The problem that the question describes, cannot be solved using query-selectors alone. This is because of following reasons:
The query selectors always works on descendants, so while evaluating that the child div has data-child-gender="true", there will be no way to return the parent element. The query-selector will return the child div.
There is no way to evaluate the inner text or contained text of an element in query-selector.
These two limitations can be worked around by using JavaScript, provided that you were going to use the query-selector in JS.
Something like the following snippet should work.
document.querySelectorAll('div[data-parent=true] div[data-child-gender=true]')
.filter(function(elem) {
return elem.innerText === 'male'; // filter the elements containing male string.
})[0].parentElement; // return the parent of matched element.
An equivalent logic could be derived for selenium too. Otherwise if this much logic is unacceptable, you can always use the much richer xpath selectors. xpath wouldn't have either of the limitations mentioned above.

How to check if inner <div> has text

what I'm trying to do is to check if my inner <div> has a text for example Ended and then remove if it has a text. I have multiple <div> with the same class name. I tried using .filter(). I would like to remove the div container_one that contains the found element.
Here is my HTML:
var $filstatus = $('.status').filter(function() {
return $(this).text() == 'Ended';
});
$filstatus.remove();
<div class="main_container">
<div class="container_one">
<div class="inner_container">
<div class="status">Ended</div>
</div>
</div>
<div class="container_one">
<div class="inner_container">
<div class="status">On going</div>
</div>
</div>
<div class="container_one">
<div class="inner_container">
<div class="status">Ended</div>
</div>
</div>
</div>
Thank you for the help!

I would use the jQuery's selector by content
combined with .closest(). This might be the shortest way:
$('.status:contains("Ended")', $('.main_container')).closest('.container_one').remove();
First ('.status:contains("Ended")') will select all elements that have a class status, contain the text "Ended" and are children of main_container (not needed but is recommended to speed up selection of elements on complex pages).
Then the method .closest('container_one') will climb up the parents tree for each of the elements from the previous step and select the first parent element with class 'container_one'.
At last it will remove all elements found.
Note: all those methods work both with single element and collections of elements, so no need of any for/foreach.
Working JSFiddle Demo

Pure JavaScript solution with forEach:
var div = document.querySelectorAll('.container_one');
div.forEach(function(el){
var target = el.querySelector('.status');
if(target.textContent == 'Ended'){
el.remove();
};
})
<div class="main_container">
<div class="container_one">
<div class="inner_container">
<div class="status">Ended</div>
</div>
</div>
<div class="container_one">
<div class="inner_container">
<div class="status">On going</div>
</div>
</div>
<div class="container_one">
<div class="inner_container">
<div class="status">Ended</div>
</div>
</div>
</div>

Try this
$filstatus.parent().parent().remove();

filter will return an array , then use each to loop over that and delete the element. In this case it will remove that specific div but the parent div will still be in dom
var $filstatus = $('.status').filter(function() {
return $(this).text().trim() === 'Ended';
});
$filstatus.each(function(index, elem) {
$(elem).remove();
})
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="main_container">
<div class="container_one">
<div class="inner_container">
<div class="status">Ended</div>
</div>
</div>
<div class="container_one">
<div class="inner_container">
<div class="status">On going</div>
</div>
</div>
<div class="container_one">
<div class="inner_container">
<div class="status">Ended</div>
</div>
</div>
</div>

If you want to remove .container_one whose inner child has the text Ended, try
const ended = $('.status').filter((index, element) => $(element).text() === 'Ended')
ended.parents('.container_one').remove()

Since you want to remove the closest ansistor with class .container_one, you will need to use closest
$filstatus.closest(".container_one").remove();
Check this: https://jsfiddle.net/n3d5fwqj/1/
https://api.jquery.com/closest/

Try using this if you don't need $filstatus in other places
$('.status').each(function(){
if ($(this).text() == "Ended"){
$(this).parent().parent().remove();
}
})

I see your problem is you are able to remove the child div status but what you want is to remove the entire parent div with class container_one
you can use $.each for that and use closest(class_name) to remove the parent including its child
$.each($('.status'), function(idx, div) {
if ($(this).text() == 'Ended') {
$(this).closest('.container_one').remove();
}
});
Demo
or you can continue your filter and just add .closest('.container_one') to your jquery selector
var $filstatus = $('.status').filter(function() {
return $(this).text() == 'Ended';
});
$filstatus.closest('.container_one').remove();
Demo

Can not see the first element of "getElementsByClassName"

I have this structure in my html:
<div class="miejsce">
<div class="blok3">
1
</div>
<div class="blok3" id="x">
2
</div>
<div class="blok3">
3
</div>
<div class="blok3">
4
</div>
</div>
<div class="miejsce">
<div class="blok3">
1
</div>
<div class="blok3">
2
</div>
<div class="blok3">
3
</div>
<div class="blok3" id="x">
4.
</div>
</div>
And I want to add parameter display: block to first elemets of divs with class "miejsce". I used for this getElementsByClassName and 'for' loop. See my JS:
var miejsca = document.getElementsByClassName('miejsce');
for(var i=0; i<miejsca.length; i++)
{
alert("work2");
miejsca[i].first().css('display', 'block');
}
Alert "work" was shown only once so problem is probably with:
miejsca[i].first().css('display', 'block');
Do you see any mistakes in my code? Please explain.

jQuery functions are not directly available on DOM elements. You need to wrap them in a jQuery object.
You can simplify all your code to this
$('.miejsce div:first-child').css('display', 'block');