Develop Reference

Calculate div width/height when inside a zoom/scale transform

I have a div inside another div with transform scale applied.
I need to get the width of this div after the scale has been applied. The result of .width() is the original width of the element.
Please see this codepen:
https://codepen.io/anon/pen/ZMpBMP
Image of problem:
Hope this is clear enough, thank you. Code below:
HTML
<div class="outer">
<div class="inner">
</div>
</div>
CSS
.outer {
height: 250px;
width: 250px;
background-color: red;
position: relative;
overflow: hidden;
}
.inner {
background-color: green;
height: 10px;
width: 10px;
transform: translate(-50%);
position: absolute;
top: 50%;
left: 50%;
transform: scale(13.0);
}
JS
$(function() {
var width = $('.inner').width();
// I expect 130px but it returns 10px
//
// I.e. It ignores the zoom/scale
// when considering the width
console.log( width );
});

Use getBoundingClientRect()
$(function() {
var width = $('.inner')[0].getBoundingClientRect();
// I expect 130px but it returns 10px
//
// I.e. It ignores the zoom/scale
// when considering the width
console.log(width.width);
});
https://jsfiddle.net/3aezfvup/3/

i achieved your 130 by this
var x = document. getElementsByClassName('inner');
var v = x.getBoundingClientRect();
width = v.width;

You need the calculated value. This can be done in CSS.
Use calc() to calculate the width of a <div> element which could be any elements:
#div1 {
position: absolute;
left: 50px;
width: calc(100% - 100px);
border: 1px solid black;
background-color: yellow;
padding: 5px;
text-align: center;
}
I found this about this topic.
Can i use Calc inside Transform:Scale function in CSS?
For JS:
How do I retrieve an HTML element's actual width and height?

How to prevent get over other divs?

I have a problem...In the following example i don't want that the div who is fixed get over the div with the background red.
Here is the example:
http://jsfiddle.net/HFjU6/3645/
#fixedContainer
{
background-color:#ddd;
position: fixed;
width: 200px;
height: 100px;
left: 50%;
top: 0%;
margin-left: -100px; /*half the width*/
}

Alright, I think I get what the OP wants. He wanted a container that stays fixed on the top of the viewport, but remains confined by a parent. This behaviour is known as a conditional sticky behaviour, and is actually implemented in both Firefox (without vendor prefix) and macOS/iOS Safari (with -webkit- prefix): see position: sticky.
Therefore the easiest (but also the least cross-browser compatible) way is simply to modify your markup, such that the sticky element stays within a parent, and you declare position: sticky on it:
* {
margin: 0;
padding: 0;
}
#fixedContainer {
background-color: #ddd;
position: -webkit-sticky;
position: sticky;
width: 200px;
height: 100px;
left: 50%;
top: 0%;
transform: translate(-50%, 0); /* Negative left margins do not work with sticky */
}
#div1 {
height: 200px;
background-color: #bbb;
}
#div1 .content {
position: relative;
top: -100px; /* Top offset must be manually calculated */
}
#div2 {
height: 500px;
background-color: red;
}
<div id="div1">
<div id="fixedContainer">I am a sticky container that stays within the sticky parent</div>
<div class="content">Sticky parent</div></div>
<div id="div2">Just another element</div>
An alternative would be to use a JS-based solution. In this case, you do not actually have to modify your markup. I have changed the IDs for easier identification of the elements, however.
The gist of the logic is this:
When the scroll position does not exceed the bottom of the parent minus the outer height of the sticky content, then we do not do anything.
When the scroll position exceeds the bottom of the parent minus the outer height of the sticky content, we dynamically calculate the top position of the sticky content so that it remains visually in the parent.
$(function() {
$(window).scroll(function() {
var $c = $('#sticky-container'),
$s = $('#sticky-content'),
$t = $(this); // Short reference to window object
if ($t.scrollTop() > $c.outerHeight() - $s.outerHeight()) {
$s.css('top', $c.offset().top + $c.outerHeight() - $t.scrollTop() - $s.outerHeight());
} else {
$s.css('top', 0);
}
});
});
* {
margin: 0;
padding: 0;
}
div {
height: 500px;
background-color: red;
}
#sticky-container {
background-color: #bbb;
height: 200px;
}
#sticky-content {
background-color: #ddd;
position: fixed;
width: 200px;
height: 100px;
margin-left: -100px;
left: 50%;
top: 0;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div id="sticky-content">Sticky content that stays within the bounds of #div1</div>
<div id="sticky-container">Sticky confinement area</div>
<div>Other content</div>
Old answer before OP clarified the question appropriately:
Just give them the appropriate z-index values. In this case, you want to:
Do not use static positioning. This can be done by using position: relative for the large elements, in conjunction with the originally position: fixed element.
Assign the appropriate stacking order. The grey <div> element to have the lowest z-index, followed by the position fixed element, and then by the red element.
There are some catchalls to stacking though: the stacking context is reset when you traverse up or down the node tree. For example, the example will not work if the elements are not siblings.
Here is a proof-of-concept example, modified from your fiddle so that inline CSS is removed.
* {
margin: 0;
padding: 0;
}
#fixedContainer {
background-color: #ddd;
position: fixed;
width: 200px;
height: 100px;
left: 50%;
top: 0%;
margin-left: -100px;
z-index: 2;
}
#div1 {
height: 200px;
background-color: #bbb;
position: relative;
z-index: 1;
}
#div2 {
height: 500px;
background-color: red;
position: relative;
z-index: 3;
}
<div id="fixedContainer">z-index: 2</div>
<div id="div1">z-index: 1</div>
<div id="div2">z-index: 3</div>

Just give the z-index.
Hope it helps...
http://jsfiddle.net/HFjU6/1/#run
#fixedContainer {
background-color:#ddd;
position: fixed;
width: 200px;
height: 100px;
left: 50%;
top: 0%;
margin-left: -100px; /*half the width*/
z-index: 2;
}
.div-red {
position: relative;
z-index: 5;
}
<div id="fixedContainer"></div>
<div style="height:200px;background-color:#bbb;"></div>
<div style="height:500px;background-color:red;" class="div-red"></div>

How to add a child element that ignores the left marging and padding of the parent in Javascript

Please take a look at this jsfiddle:
http://jsfiddle.net/dd4g4re5/
This is the code:
HTML
<div class="a"></div>
CSS
div{
width: 200px;
height: 200px;
background: red;
}
.a {
padding-left: 6px;
}
.b {
position: relative;
background: blue;
}
JAVASCRIPT
var divA = document.getElementsByTagName("div")[0];
var divB = document.createElement("div");
divB.className="b";
divA.appendChild(divB);
I want to position the child div in top of the
container div, so it completely overlap the parent.
But as you can see, that is not possible because of the
left padding of the parent.
I guess I could do something like this:
divB.style.left = -(divA.leftPadding + divA.leftMargin)+"px";
But I hope there is a batter way to do that, like some native function in Javascript, so I don't
have to make that kind of calculations.
Also, I would like to avoid setting the child an absolute position.

Using border-box here will make sure they both fit the desired widths. And you'll want to give the child element a negative left margin the same value as it's parent left padding.
var divA = document.getElementsByTagName("div")[0];
var divB = document.createElement("div");
divB.className="b";
divA.appendChild(divB);
div{
width: 200px;
height: 200px;
background: red;
-webkit-box-sizing: border-box;
-moz-box-sizing: border-box;
box-sizing: border-box;
}
.a {
padding-left: 6px;
}
.b {
position: relative;
background: blue;
margin-left: -6px;
}
<div class="a"></div>

You could position the child absolutely within the (relative) parent, like so:
.parent {
position: relative;
padding: 10px;
}
.child {
position: absolute;
top: 0;
left: 0;
width: 100%;
height: 100%;
}
http://jsfiddle.net/bvaughn/ouxsdmfc/

Keep width of container that of the longest child

In short: When I have a container and some inline-block divs, the container's width shrinks around the divs. But when the divs are too-long and therefore one of them goes to another line, the container width is rendered as 100%.
In the picture the default behavior is the first one, whereas the desired behavior is the second one.
Here is a fiddle with the example:
http://jsfiddle.net/gzbx4upq/
See fiddle for desired results

Either use
display:block;
or
display:inline;
or
max-width:250px ;

That seems possible using pseudo classes.
CSS
div {
display: inline;
position: relative;
}
div:before {
content:"";
position: absolute;
left: 0px;
right: 0px;
bottom: -5px;
top: -5px;
background-color: blue;
z-index:-1;
}
div:after {
content:"";
display: block;
}
p {
display: inline-block;
background-color: red;
}
Working Fiddle

How can I create many divs on on top of the other using CSS/jQuery?

Basically, I want many(>25) divs to be displayed one on top of the other so that only one can be seen at a time. I have the jQuery UI draggable implemented, so once a div is dragged away, the next div is shown. What CSS do I need to make such a stack of divs? jQuery is also available if required.
Thanks!

Try this:
CSS
div.square {
cursor: pointer;
width: 100px;
height: 100px;
border: 2px dashed purple;
position: absolute;
top: 30px;
left: 30px;
font-size: 50px;
line-height: 100px;
text-align: center;
color: white;
}
jQuery + jQueryUI
var count = 25;
var colors = ['red','green','blue','orange','yellow'];
while(count--) {
$('<div/>',{className:'square', text:count}).draggable().css({position:'absolute','z-index':count, text:count, backgroundColor:colors[count % 5]})
.appendTo('body');
}
EDIT:
I just noticed that for some reason in IE and Safari .draggable() overrides the absolute positioning with relative, so you need to set it back to absolute after you made it draggable.
Updated the example above.
http://jsfiddle.net/p9wWA/

You mean something like this?
#relative_container { position: relative; }
#relative_container div { position: absolute; top: 0; left: 0; width: 100px; height: 100px; }
#relative_container div.item_1 { z-index: 100; } /* Higher index means its more on top */