We Keep Coding

How can i click and just own class can be shown on Javascript

<div class="item text-center">
<div class="class1"> <p> Something </p> </div>
</div>
<div class="item text-center">
<div class="class1"> <p> Something </p> </div>
</div>
$(".class1").hide();
$(".item").click(function () {
$(".class1").show();
})
I want that when the user click div of item, its own class1 should be show();
But in my codes, when the user click item of div, all class1 shows.
How can i do that just own class can be shown?

To fix this you need to use DOM traversal to access the .class1 element(s) within the clicked .item. To do that you can use the this keyword within the event handler to access the element which raised the event. Try this:
$(".item").click(function() {
$(this).find(".class1").show();
})
.class1 { display: none; }
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div class="item text-center">
Foo
<div class="class1">
<p> Something </p>
</div>
</div>
<div class="item text-center">
Bar
<div class="class1">
<p> Something </p>
</div>
</div>
Note in the example that I used CSS to hide the .class1 elements instead of JS. This is because JS runs after the DOM has loaded, so can result in elements being visible for a short time before they are hidden. CSS runs before this, so avoids that occurrence.

$(".class1").hide();
$(".item").click(function () {
$(this).find(".class1").show();
});
<!--The parent divs should not be empty, otherwise when later in the code you call the .hide () method on their respective child divs, there would be nothing left to click on-->
<div class="item text-center">
item1
<div class="class1">
<p> Something </p>
</div>
</div>
<div class="item text-center">
item2
<div class="class1">
<p> Something </p>
</div>
</div>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
You can use the find () method, the find () method returns the descendant elements of the selected element. Like the code above

jQuery element removal

I want to remove an element using jQuery.
HTML:
<div class="listContainer" id="listContainer">
<div class="listItem">
<div class="name">
Item Name
</div>
<div class="amount">
<input type="text" class="amountInput" />
</div>
<div class="delete">
<div class="deleteBtn">
X
</div>
</div>
</div>
</div>
There are several listItemss on the page and each of the listItem will be created dynamically using jQuery. I want to delete amountInput of specific listItem by clicking the deleteBtn, so I tried doing:
$("#listContainer").on("click", ".deleteBtn", function() {
$(this).closest(".amountInput").remove();
});
This doesn't work. But on the other hand if I try to delete a listItem as a whole, the code works:
$("#listContainer").on("click", ".deleteBtn", function() {
$(this).closest(".listItem").remove();
});
Why is this happening?
Thanks.

Because .closest propagates to the top of the HTML. So it searches for the first parent that matches your selector. That is why it cannot find .amountInput. Because it isn't a parent of your button.
To get .amountInput you have to:
$("#listContainer").on("click", ".deleteBtn", function() {
$(this).closest(".listItem").find('.amountInput').remove();
});
This will get the wrapping .listItem element and then search it for the .amountInput element.

Your selector is not correct, use find instead of closest could be helpful in this case, also $(this) in your sample is related to deleteBtn class not to listContainer.
$("#listContainer").on("click", ".deleteBtn", function() {
console.log($(this)) // this here is .deleteBtn not listContainer
$(this).closest(".listItem").find(".amountInput").remove();
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div class="listContainer" id="listContainer">
<div class="listItem">
<div class="name">
Item Name
</div>
<div class="amount">
<input type="text" class="amountInput" />
</div>
<div class="delete">
<div class="deleteBtn">
X
</div>
</div>
</div>
</div>

Enclose whole div in an <a>

I have a div which I want to surround with an <a href>. I have the jQuery to add the <a href> after the div but I struggle to set it before and close it after the div.
This is the jQuery code I have:
$('.box_service').each(function() {
var link = $(this).html();
$(this).contents().wrap('');
});
It results in this HTML:
<div class="row">
<div class="box_service">
<a href="example.com">
<div class="inner-row"></div>
</a>
</div>
</div>
However my goal is this structure:
<div class="row">
<a href="example.com">
<div class="box_service">
<div class="inner-row"></div>
</div>
</a>
</div>
I can't enter the div before because there are more boxes in this row so I would add the <a href> to everything in there

The issue is due to your call to contents() which means you're wrapping the elements inside .box_service, not that element itself. Remove that method call.
Also note that each() is redundant, you can do what you require in a single line:
$('.box_service').wrap('');
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div class="row">
<div class="box_service">
Box service #1
<div class="inner-row">Inner row #1</div>
</div>
</div>
<div class="row">
<div class="box_service">
Box service #2
<div class="inner-row">Inner row #2</div>
</div>
</div>

.content will wrap the contents of your div, you want to wrap the div with <a> so call wrap on the div not on contents.
$('.box_service').each(function() {
var link = $(this).html();
$(this).wrap('');
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div class="row">
<div class="box_service">
<div class="inner-row"></div>
</div>
</div>

$('.box_service').each(function() {
var link = $(this).html();
$(this).wrap('');
});
You just need to remove contents() in between $(this).wrap() because contents() mean that you are wrapping the children of $(this).

Remove .contents() in order to wrap around each element with the class box-service:
$('.box_service').each(function() {
$(this).wrap('');
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div class="row">
<div class="box_service">
<a href="example.com">
<div class="inner-row"></div>
</a>
</div>
</div>

$('.box_service').wrap('');

Hiding an element through DOM traversal

What if it has few parents? (as in grandparents, great grandparents)
<div class="lvl1">
<div class="lvl1.1">
<div class="lvl1.2">
<button class="btn-submit">Click Me</button>
<div class="a1">Hello
<div>
</div>
</div>
<div class="lvl2">
<div class="b1">
<div class="b2">Make me disappear!</div>
</div>
</div>
<div class="lvl3">
<div class="c1">Thank you.
</div>
</div>
JS
$(function(){
$(".btn-submit").click(function() {
$(this).parent(".lvl1").siblings(".lvl2").children(".b2").hide();
});
});
How to use .parent, .parents, .siblings, .children, .next, .prev to show and hide the div?

If I assume that you have that structure repeated and want to remove the one in the same copy as the .btn_submit that was clicked, we go up to the .lvl1 via closest, over to the .lvl2 via .nextAll().first() (or we could just use .next), and then .find the .b2 in there:
$(".btn-submit").click(function() {
$(this).closest(".lvl1").nextAll(".lvl2").first().find(".b2").hide();
});
Your code is very close, just two things that I had to change:
Instead of using .siblings(".lvl2"), which will find all of them, I used .nextAll(".lvl2").first() to just find the one immediately after "this" .lvl1.
I used find instead of children, because children will only go down one level (direct child), not search descendants
I also used closest(".lvl1") so that if you move the .btn_submit deeper into .lvl1, it will continue working.
Live Example:
$(function() {
$(".btn-submit").click(function() {
$(this)
.closest(".lvl1")
.nextAll(".lvl2")
.first()
.find(".b2")
.hide();
});
});
<div class="lvl1">
<button class="btn-submit">Click Me</button>
<div class="a1">Hello
</div>
</div>
<div class="lvl2">
<div class="b1">
<div class="b2">Make me disappear!</div>
</div>
</div>
<div class="lvl3">
<div class="c1">Thank you.
</div>
</div>
<div class="lvl1">
<button class="btn-submit">Click Me</button>
<div class="a1">Hello
</div>
</div>
<div class="lvl2">
<div class="b1">
<div class="b2">Make me disappear!</div>
</div>
</div>
<div class="lvl3">
<div class="c1">Thank you.
</div>
</div>
<div class="lvl1">
<button class="btn-submit">Click Me</button>
<div class="a1">Hello
</div>
</div>
<div class="lvl2">
<div class="b1">
<div class="b2">Make me disappear!</div>
</div>
</div>
<div class="lvl3">
<div class="c1">Thank you.
</div>
</div>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>

there is possible to disappear div directly using,
$(".b2").hide();
but if you want to use ".parent, .parents, .siblings, .children, .next, .prev",
$(".btn-submit").parent().siblings(".lvl2").children().children(".b2").hide();
need to you children() Two times... because .b2 is not directly child to .lvl2,
another best way to hide ".b2" is,
$(".btn-submit").parent().siblings(".lvl2").find(".b2").hide();
so your Ans is:
$(".btn-submit").click(function() {
$(".btn-submit").parent().siblings(".lvl2").find(".b2").hide();
});

.children selects the children and not descendants of the element. You just need to replace the .children with the .find method and your code will select the target element.

Appending element to the sibling

how to append element into the closest on clicking "add-picture" button?
This is the html structure:
<div class="step"
<div class="step-wrapper>
<div class="editor"></div>
</div>
<div class="delete-picture">
<div class="add-picture">
</div>
<div class="step"
<div class="step-wrapper>
<div class="editor"></div>
</div>
<div class="delete-picture">
<div class="add-picture">
</div>
<div class="step"
<div class="step-wrapper>
<div class="editor"></div>
</div>
<div class="delete-picture">
<div class="add-picture">
</div>
and here is my wrong jquery:
$(document).on('click', '.add-picture', function() {
var imageField = $('<img class="link" >');
$(this).parent().find(".step-wrapper").after(imageField);
});
after click .step should look like:
<div class="step"
<div class="step-wrapper>
<img class="link" >
<div class="editor"></div>
</div>
<div class="delete-picture">
<div class="add-picture">
</div>

I think you want .prepnd(), not .after() to make it the first child element.
$(document).on('click', '.add-picture', function() {
var imageField = $('<img class="link" >');
$(this).parent().find(".step-wrapper").prepend(imageField);
});
See the jQuery doc for .prepend().
Though this style of code works, you could also use .closest() for slightly more robust code:
$(document).on('click', '.add-picture', function() {
var imageField = $('<img class="link" >');
$(this).closest(".step").find(".step-wrapper").prepend(imageField);
});

Use prepend() instead of after():
$(this).parent().find(".step-wrapper").prepend(imageField);
after() places the content as a sibling whereas prepend() makes it the first child element

Looks like you want to add the element before the .editor element, so try
$(document).on('click', '.add-picture', function() {
var imageField = $('<img class="link" >');
$(this).parent().find(".step-wrapper .editor").before(imageField);
});
Demo: Fiddle

2 Working demo: http://jsfiddle.net/E78VA/1/ & http://jsfiddle.net/E78VA/
Also plz note your html DOM was not right and have few minor mistakes I have rectified ur HTML as well. i.e. missing end div etc. :)
APIs could be used are
prependTo http://api.jquery.com/prependTo/
prepend http://api.jquery.com/prepend/
Hope rest fits the cause :)
Code
$(document).on('click', '.add-picture', function () {
var imageField = $('<img class="link" >');
// $(this).parent().find(".step-wrapper").prepend(imageField);
$(imageField).prependTo($(this).parent().find(".step-wrapper"));
alert($(this).parent().find(".step-wrapper").html());
});
HTML
<div class="step">
<div class="step-wrapper">
<div class="editor">test</div>
</div>
<div class="delete-picture">delete</div>
<div class="add-picture">add</div>
</div>
<div class="step">
<div class="step-wrapper">
<div class="editor"></div>
</div>
<div class="delete-picture"></div>
<div class="add-picture"></div>
</div>
<div class="step">
<div class="step-wrapper">
<div class="editor"></div>
</div>
<div class="delete-picture"></div>
<div class="add-picture"></div>
</div>