Develop Reference

How can I float an element on scroll, with delay?

I have the following div floating but I want as the green element inside left panel to have a delay about half second.
Does anyone any idea how can I do this?
https://jsfiddle.net/eoopvgmc/22/
This is the code which is floating the elements on scroll
$(document).ready(function() {
var offset = $('.ads').offset().top, top;
$(document).on('scroll', function() {
top = $(window).scrollTop() < offset ? '0' : $(window).scrollTop() - offset + 'px';
$('.ads').css({
'top': top
});
})
});

To make the .element independent transition, you need to move it out of the .left-zone element.
$(document).ready(function () {
var offset = $('.ads').offset().top,
top;
$(document).on('scroll', function () {
top = $(window).scrollTop() < offset ? '0' : $(window).scrollTop() - offset;
console.log(top);
$('.ads').css({
'top': top
});
$('.element').css({
'top': +top + 50
});
})
});
Working Fiddle

I managed to get something like what you describe working by adding some transition effects to the element and using a little delay, you should be able to tweak the timeout, margin-top and transition values to get exactly what you want:
$(document).ready(function() {
var offset = $('.ads').offset().top, top;
$(document).on('scroll', function() {
top = $(window).scrollTop() < offset ? '0' : $(window).scrollTop() - offset + 'px';
$('.ads .element').css({
'transition': 'none',
'margin-top': '-60px'
});
$('.ads').css({
'top': top
});
setTimeout(function() {
$('.ads .element').css({
'transition': 'margin-top 3s',
'margin-top': '0'
});
});
})
});
Fiddle: https://jsfiddle.net/yckszc16/

Since the element is absolute positioned, I took it that it does not need to be nested within the div. Therefore I changed the HTML from this:
<div class="left-zone ads">
<div class="element"></div>
</div>
to this:
<div class="left-zone ads"></div>
<div class="element"></div>
I then adjusted the css to position the element in the same place as it was, like so:
.element{
position: absolute;
top: 60px;
left: -71px;
width: 20px;
height: 30px;
background: green;
}
This allows the object to be manipulated completely seperately to the parent, which also makes it much more flexible in what you can do with it.
To get the animation going on it, I had to change a few bits of code.
Where you were setting the top variable, I removed the + 'px' at the end to allow for the setting of different values in each animation. This is required because the element must have it's top value (60px in this case) added to the animation to keep it in the correct position. I then copied the code that sets the animation going and repeated it for the 'element' div, and added the 60px to it. if that doesn't make sense then check out the code below.
$(document).on('scroll', function() {
top = $(window).scrollTop() < offset ? '0' : $(window).scrollTop() - offset;
$('.ads').css({
'top': top + 'px'
});
$('.element').css({
'top': top + 60 + 'px'
});
})
Next is to get the delay. I first tried the jquery .delay function but it didn't seem to work so I made an even simpler change, add the transition line from your 'ads' div to the 'element' div's css and change the duration to half a second longer. This achieves the required effect of it coming in afterwards! Here is the code:
.element{
position: absolute;
top: 60px;
left: -71px;
width: 20px;
height: 30px;
background: green;
transition: top 1.3s;
}
Here is a jsfiddle if you want to see it in action: https://jsfiddle.net/hdn1oyjd/
Let me know if you have any questions!

How do I script such that my panoramic image can be panned left and right up to its edges?

Say my image (panoramic) is 10,000 pixels long, but I want to be able to view only 1000 pixels wide at a time, and in order to view more of it, I can just hover my mouse either left or right, and then the image will move accordingly please? If possible, a simple script on HTML? (I'm not sure how to use Javascript or CSS, but if it needs to come down to that, do guide me step by step?
Thank you.

Here is a simple JQuery which you can use to scroll the whole page when hovering over either the left or right;
Example - https://jsfiddle.net/38da9pca/
Need any help implementing it just leave a comment and I will try and help you.
$(function() {
$('#right').on('mouseenter', rscroll);
$('#left').on('mouseenter', lscroll);
$('#right, #left').on('mouseleave', function() {
$('body').stop();
});
function rscroll() {
$('body').animate({
scrollLeft: '+=25'
}, 10, rscroll);
}
function lscroll() {
$('body').animate({
scrollLeft: '-=25'
}, 10, lscroll);
}
});
Edit (Scroll Image Only)
Example - https://jsfiddle.net/38da9pca/1/
I have change it so the lscroll and the rscroll will effect the id of image instead of the body and change it from scrollLeft to left, and that way it will move the images scroll. Dont forgot to change the $('body').stop(); to $('#bg').stop(); or it will never stop scrolling
$(function() {
$('#right').on('mouseenter', rscroll);
$('#left').on('mouseenter', lscroll);
$('#right, #left').on('mouseleave', function() {
$('#bg').stop();
});
function rscroll() {
$('#bg').animate({
left: '-=25'
}, 10, rscroll);
}
function lscroll() {
$('#bg').animate({
left: '+=25'
}, 10, lscroll);
}
});

Here's one. It's using jquery (javascript library). You would have to add it in order to make it work.
Example:
http://www.gayadesign.com/scripts/jqueryphotonav/
Tutorial:
https://blog.gaya.ninja/articles/jquery-convertion-panoramic-photoviewer-in-javascript/

Something like this?
var imgView = document.querySelectorAll('.img-view')[0];
var img = imgView.querySelectorAll('img')[0];
imgView.onmousemove = function(e) {
var x = e.clientX;
var px = ((x / this.offsetWidth) * 100);
var ix = ((px / 100) * img.offsetWidth);
img.style.left = '-' + (ix - this.offsetWidth) + 'px';
}
.img-view {
width: 256px;
height: 160px;
overflow: hidden;
position: relative;
border: 1px solid #ddd;
}
.img-view img {
height: 100%;
position: relative;
top: 0;
left: 0;
}
<div class="img-view">
<img src="http://panoramalove.com/wp-content/uploads/2013/01/nighttime-panoramic-view-of-hong-kong-island-from-the-avenue-of-stars-in-tsim-sha-tsui.jpg">
</div>

Setting re-size boundaries

I have a horizontally re-sizable side-bar which itself is composed of two sections which are vertically re-sizable (here's how my-JSFiddle)
I achieved this by adding divs which act as draggable re-sizing handlers and then I can act on it's mouse events ..
$(document).mousemove(function(e){
$('#content').css("width",e.pageX+2);
('#history').css("left",e.pageX+2);
})
Now I wish to apply the following constraints:
min width on the side bar, such that I cannot completely collapse the side-bar
min and max height on the two sections of the side bar.
These constraints are similar to those in JSFiddle itself ..
Will I have to do this via JavaScript only or is there a way to achieve this via CSS.

i added a new FIDDLE for you
in your case you have to check the current width and select the min width or height from css
like this
....
var cvmw = parseInt($('#content').css('min-width'));
....
and than check if its reached
$(document).mousemove(function (e) {
// get current with
var w = parseInt($('#content').css("width"));
// check if with bigger than min-with
if (w > cvmw) {
$('#content').css("width", e.pageX + 2);
$('#history').css("left", e.pageX + 2);
} else {
$('#content').css("width", cvmw + 1);
$('#history').css("left", cvmw + 1);
$(document).unbind('mousemove');
}
})
here the changed css, there are some more changes made for each section
#content {
background-color: WhiteSmoke;
width:75%;
height: 80%;
min-width: 100px; /* added this min-width for further actions */
float: left;
position: absolute;
top:30px;
bottom: 100px;
}
guess you can do some other actions to keep the mouse bind to drag when hovering something like the dragline

Re-sizing the webpage content

In my project I have a webpage which has 2 div areas right and left. The left div takes almost 60% of the whole page width and the right one takes around 36% of the page. I wanted to resize the both div areas in a proper ratio when I shrink the browser from the right side or left side. The UI is getting generated from Javascript. This is the code.
boardHolderPadding = $board.outerHeight() - $board.height();
$board.height(viewportHeight - siblingsHeight - boardHolderPadding);
this.$('#board .droptarget').setWidthAsRatioOfHeight(this.options.ratio);
$('#sidebar').width($(window).width() - $board.find('#board').width() - 50);
I tried with JQuery resize plugin but couldnt get the proper result I'm looking for. Anyone have suggestion?
Thanks

See jsfiddle example but I think you just need to set your widths as percentages rather than trying to calculate them - note display is set to inline-block
<div>
<div class="small-left-column">this is the left column</div>
<div class="large-right-column">this is the right column</div>
</div>
<style>
.small-left-column {
width: 30%;
background-color: #aeaeae;
display: inline-block;
}
.large-right-column {
width: 60%;
background-color: #aeaeae;
display: inline-block;
}
</style>
So I think for your example your would have something like this
$(document).ready(function () {
$('#sidebar').addClass('small-left-column');
$('#board').addClass('large-right-column');
});

Maybe you're looking for the pure-Javascript version of the above:
$(document).ready(function () {
$('#sidebar').css( {
width: '30%'
backgroundColor: '#aeaeae',
display: 'inline-block'
});
$('#board').css({
width: '60%',
backgroundColor: '#aeaeae',
display: 'inline-block'
});
});

I did it in a different way in Javascript and I hope this will help someone to fix if they come across an issue like that
relativeSize : function(width, height){
var boardWidth = this.$("#board").width(),
boardHeight = this.$("#board").height(),
newcard = this.$("#newCard").width(),
space = width - boardWidth - newcard;
ratio = space / width * 3; //used to increment the ratio with 3 as the ratio is very tiny value, this will help to increase minimizing size
bheight = boardHeight - 25; // used to reduce the height by 25px, u can use any amount to match ur ratio
var relHeight = (space < ratio) ? bheight : height;
return relHeight;
}
Thanks

Using jQuery to center a DIV on the screen

How do I go about setting a <div> in the center of the screen using jQuery?

I like adding functions to jQuery so this function would help:
jQuery.fn.center = function () {
this.css("position","absolute");
this.css("top", Math.max(0, (($(window).height() - $(this).outerHeight()) / 2) +
$(window).scrollTop()) + "px");
this.css("left", Math.max(0, (($(window).width() - $(this).outerWidth()) / 2) +
$(window).scrollLeft()) + "px");
return this;
}
Now we can just write:
$(element).center();
Demo: Fiddle (with added parameter)

I put a jquery plugin here
VERY SHORT VERSION
$('#myDiv').css({top:'50%',left:'50%',margin:'-'+($('#myDiv').height() / 2)+'px 0 0 -'+($('#myDiv').width() / 2)+'px'});
SHORT VERSION
(function($){
$.fn.extend({
center: function () {
return this.each(function() {
var top = ($(window).height() - $(this).outerHeight()) / 2;
var left = ($(window).width() - $(this).outerWidth()) / 2;
$(this).css({position:'absolute', margin:0, top: (top > 0 ? top : 0)+'px', left: (left > 0 ? left : 0)+'px'});
});
}
});
})(jQuery);
Activated by this code :
$('#mainDiv').center();
PLUGIN VERSION
(function($){
$.fn.extend({
center: function (options) {
var options = $.extend({ // Default values
inside:window, // element, center into window
transition: 0, // millisecond, transition time
minX:0, // pixel, minimum left element value
minY:0, // pixel, minimum top element value
withScrolling:true, // booleen, take care of the scrollbar (scrollTop)
vertical:true, // booleen, center vertical
horizontal:true // booleen, center horizontal
}, options);
return this.each(function() {
var props = {position:'absolute'};
if (options.vertical) {
var top = ($(options.inside).height() - $(this).outerHeight()) / 2;
if (options.withScrolling) top += $(options.inside).scrollTop() || 0;
top = (top > options.minY ? top : options.minY);
$.extend(props, {top: top+'px'});
}
if (options.horizontal) {
var left = ($(options.inside).width() - $(this).outerWidth()) / 2;
if (options.withScrolling) left += $(options.inside).scrollLeft() || 0;
left = (left > options.minX ? left : options.minX);
$.extend(props, {left: left+'px'});
}
if (options.transition > 0) $(this).animate(props, options.transition);
else $(this).css(props);
return $(this);
});
}
});
})(jQuery);
Activated by this code :
$(document).ready(function(){
$('#mainDiv').center();
$(window).bind('resize', function() {
$('#mainDiv').center({transition:300});
});
);
is that right ?
UPDATE :
From CSS-Tricks
.center {
position: absolute;
left: 50%;
top: 50%;
transform: translate(-50%, -50%); /* Yep! */
width: 48%;
height: 59%;
}

I would recommend jQueryUI Position utility
$('your-selector').position({
of: $(window)
});
which gives you much more possibilities than only centering ...

Here's my go at it. I ended up using it for my Lightbox clone. The main advantage of this solution is that the element will stay centered automatically even if the window is resized making it ideal for this sort of usage.
$.fn.center = function() {
this.css({
'position': 'fixed',
'left': '50%',
'top': '50%'
});
this.css({
'margin-left': -this.outerWidth() / 2 + 'px',
'margin-top': -this.outerHeight() / 2 + 'px'
});
return this;
}

You can use CSS alone to center like so:
Working Example
.center{
position: absolute;
height: 50px;
width: 50px;
background:red;
top:calc(50% - 50px/2); /* height divided by 2*/
left:calc(50% - 50px/2); /* width divided by 2*/
}
<div class="center"></div>
calc() allows you to do basic calculations in css.
MDN Documentation for calc()
Browser support table

I'm expanding upon the great answer given by #TonyL. I'm adding Math.abs() to wrap the values, and also I take into account that jQuery might be in "no conflict" mode, like for instance in WordPress.
I recommend that you wrap the top and left values with Math.abs() as I have done below. If the window is too small, and your modal dialog has a close box at the top, this will prevent the problem of not seeing the close box. Tony's function would have had potentially negative values. A good example on how you end up with negative values is if you have a large centered dialog but the end user has installed several toolbars and/or increased his default font -- in such a case, the close box on a modal dialog (if at the top) might not be visible and clickable.
The other thing I do is speed this up a bit by caching the $(window) object so that I reduce extra DOM traversals, and I use a cluster CSS.
jQuery.fn.center = function ($) {
var w = $(window);
this.css({
'position':'absolute',
'top':Math.abs(((w.height() - this.outerHeight()) / 2) + w.scrollTop()),
'left':Math.abs(((w.width() - this.outerWidth()) / 2) + w.scrollLeft())
});
return this;
}
To use, you would do something like:
jQuery(document).ready(function($){
$('#myelem').center();
});

I would use the jQuery UI position function.
See working demo.
<div id="test" style="position:absolute;background-color:blue;color:white">
test div to center in window
</div>
If i have a div with id "test" to center then the following script would center the div in the window on document ready. (the default values for "my" and "at" in the position options are "center")
<script type="text/javascript">
$(function(){
$("#test").position({
of: $(window)
});
};
</script>

I would like to correct one issue.
this.css("top", ( $(window).height() - this.height() ) / 2+$(window).scrollTop() + "px");
Above code won't work in cases when this.height (lets assume that user resizes the screen and content is dynamic) and scrollTop() = 0, example:
window.height is 600
this.height is 650
600 - 650 = -50
-50 / 2 = -25
Now the box is centered -25 offscreen.

This is untested, but something like this should work.
var myElement = $('#myElement');
myElement.css({
position: 'absolute',
left: '50%',
'margin-left': 0 - (myElement.width() / 2)
});

I dont think having an absolute position would be best if you want an element always centered in the middle of the page. You probably want a fixed element. I found another jquery centering plugin that used fixed positioning. It is called fixed center.

Edit:
If the question taught me anything, it's this: don't change something that already works :)
I'm providing an (almost) verbatim copy of how this was handled on http://www.jakpsatweb.cz/css/css-vertical-center-solution.html - it's heavily hacked for IE but provides a pure CSS way of answering the question:
.container {display:table; height:100%; position:absolute; overflow:hidden; width:100%;}
.helper {#position:absolute; #top:50%;
display:table-cell; vertical-align:middle;}
.content {#position:relative; #top:-50%;
margin:0 auto; width:200px; border:1px solid orange;}
Fiddle: http://jsfiddle.net/S9upd/4/
I've run this through browsershots and it seems fine; if for nothing else, I'll keep the original below so that margin percentage handling as dictated by CSS spec sees the light of day.
Original:
Looks like I'm late to the party!
There are some comments above that suggest this is a CSS question - separation of concerns and all. Let me preface this by saying that CSS really shot itself in the foot on this one. I mean, how easy would it be to do this:
.container {
position:absolute;
left: 50%;
top: 50%;
overflow:visible;
}
.content {
position:relative;
margin:-50% 50% 50% -50%;
}
Right? Container's top left corner would be in the center of the screen, and with negative margins the content will magically reappear in the absolute center of the page! http://jsfiddle.net/rJPPc/
Wrong! Horizontal positioning is OK, but vertically... Oh, I see. Apparently in css, when setting top margins in %, the value is calculated as a percentage always relative to the width of the containing block. Like apples and oranges! If you don't trust me or Mozilla doco, have a play with the fiddle above by adjusting content width and be amazed.
Now, with CSS being my bread and butter, I was not about to give up. At the same time, I prefer things easy, so I've borrowed the findings of a Czech CSS guru and made it into a working fiddle. Long story short, we create a table in which vertical-align is set to middle:
<table class="super-centered"><tr><td>
<div class="content">
<p>I am centered like a boss!</p>
</div>
</td></tr></table>
And than the content's position is fine-tuned with good old margin:0 auto;:
.super-centered {position:absolute; width:100%;height:100%;vertical-align:middle;}
.content {margin:0 auto;width:200px;}​
Working fiddle as promised: http://jsfiddle.net/teDQ2/

The transition component of this function worked really poorly for me in Chrome (didn't test elsewhere). I would resize the window a bunch and my element would sort of scoot around slowly, trying to catch up.
So the following function comments that part out. In addition, I added parameters for passing in optional x & y booleans, if you want to center vertically but not horizontally, for example:
// Center an element on the screen
(function($){
$.fn.extend({
center: function (x,y) {
// var options = $.extend({transition:300, minX:0, minY:0}, options);
return this.each(function() {
if (x == undefined) {
x = true;
}
if (y == undefined) {
y = true;
}
var $this = $(this);
var $window = $(window);
$this.css({
position: "absolute",
});
if (x) {
var left = ($window.width() - $this.outerWidth())/2+$window.scrollLeft();
$this.css('left',left)
}
if (!y == false) {
var top = ($window.height() - $this.outerHeight())/2+$window.scrollTop();
$this.css('top',top);
}
// $(this).animate({
// top: (top > options.minY ? top : options.minY)+'px',
// left: (left > options.minX ? left : options.minX)+'px'
// }, options.transition);
return $(this);
});
}
});
})(jQuery);

To center the element relative to the browser viewport (window), don't use position: absolute, the correct position value should be fixed (absolute means: "The element is positioned relative to its first positioned (not static) ancestor element").
This alternative version of the proposed center plugin uses "%" instead of "px" so when you resize the window the content is keep centered:
$.fn.center = function () {
var heightRatio = ($(window).height() != 0)
? this.outerHeight() / $(window).height() : 1;
var widthRatio = ($(window).width() != 0)
? this.outerWidth() / $(window).width() : 1;
this.css({
position: 'fixed',
margin: 0,
top: (50*(1-heightRatio)) + "%",
left: (50*(1-widthRatio)) + "%"
});
return this;
}
You need to put margin: 0 to exclude the content margins from the width/height (since we are using position fixed, having margins makes no sense).
According to the jQuery doc using .outerWidth(true) should include margins, but it didn't work as expected when I tried in Chrome.
The 50*(1-ratio) comes from:
Window Width: W = 100%
Element Width (in %): w = 100 * elementWidthInPixels/windowWidthInPixels
Them to calcule the centered left:
left = W/2 - w/2 = 50 - 50 * elementWidthInPixels/windowWidthInPixels =
= 50 * (1-elementWidthInPixels/windowWidthInPixels)

This is great. I added a callback function
center: function (options, callback) {
if (options.transition > 0) {
$(this).animate(props, options.transition, callback);
} else {
$(this).css(props);
if (typeof callback == 'function') { // make sure the callback is a function
callback.call(this); // brings the scope to the callback
}
}

What I have here is a "center" method that ensures the element you are attempting to center is not only of "fixed" or "absolute" positioning, but it also ensures that the element you are centering is smaller than its parent, this centers and element relative to is parent, if the elements parent is smaller than the element itself, it will pillage up the DOM to the next parent, and center it relative to that.
$.fn.center = function () {
/// <summary>Centers a Fixed or Absolute positioned element relative to its parent</summary>
var element = $(this),
elementPos = element.css('position'),
elementParent = $(element.parent()),
elementWidth = element.outerWidth(),
parentWidth = elementParent.width();
if (parentWidth <= elementWidth) {
elementParent = $(elementParent.parent());
parentWidth = elementParent.width();
}
if (elementPos === "absolute" || elementPos === "fixed") {
element.css('right', (parentWidth / 2) - elementWidth / 2 + 'px');
}
};

CSS solution
In two lines only
It centralize your inner div horizontally and vertically.
#outer{
display: flex;
}
#inner{
margin: auto;
}
for only horizontal align, change
margin: 0 auto;
and for vertical, change
margin: auto 0;

i use this:
$(function() {
$('#divId').css({
'left' : '50%',
'top' : '50%',
'position' : 'absolute',
'margin-left' : -$('#divId').outerWidth()/2,
'margin-top' : -$('#divId').outerHeight()/2
});
});

Please use this:
$(window).resize(function(){
$('.className').css({
position:'absolute',
left: ($(window).width() - $('.className').outerWidth())/2,
top: ($(window).height() - $('.className').outerHeight())/2
});
});
// To initially run the function:
$(window).resize();

you're getting that poor transition because you're adjusting the position of the element every time the document is scrolled. What you want is to use fixed positioning. I tried that fixed center plugin listed above and that seems to do solve the problem nicely. Fixed positioning allows you to center an element once, and the CSS property will take care of maintaining that position for you every time you scroll.

Here is my version. I may change it after I look at these examples.
$.fn.pixels = function(property){
return parseInt(this.css(property));
};
$.fn.center = function(){
var w = $($w);
return this.each(function(){
$(this).css("position","absolute");
$(this).css("top",((w.height() - $(this).height()) / 2) - (($(this).pixels('padding-top') + $(this).pixels('padding-bottom')) / 2) + w.scrollTop() + "px");
$(this).css("left",((w.width() - $(this).width()) / 2) - (($(this).pixels('padding-left') + $(this).pixels('padding-right')) / 2) + w.scrollLeft() + "px");
});
};

No need jquery for this
I used this to center Div element.
Css Style,
.black_overlay{
display: none;
position: absolute;
top: 0%;
left: 0%;
width: 100%;
height: 100%;
background-color: black;
z-index:1001;
-moz-opacity: 0.8;
opacity:.80;
filter: alpha(opacity=80);
}
.white_content {
display: none;
position: absolute;
top: 25%;
left: 25%;
width: 50%;
height: 50%;
padding: 16px;
border: 16px solid orange;
background-color: white;
z-index:1002;
overflow: auto;
}
Open element
$(document).ready(function(){
$(".open").click(function(e){
$(".black_overlay").fadeIn(200);
});
});

MY UPDATE TO TONY L'S ANSWER
This is the modded version of his answer that I use religiously now. I thought I would share it, as it adds slightly more functionality to it for various situations you may have, such as different types of position or only wanting horizontal/vertical centering rather than both.
center.js:
// We add a pos parameter so we can specify which position type we want
// Center it both horizontally and vertically (dead center)
jQuery.fn.center = function (pos) {
this.css("position", pos);
this.css("top", ($(window).height() / 2) - (this.outerHeight() / 2));
this.css("left", ($(window).width() / 2) - (this.outerWidth() / 2));
return this;
}
// Center it horizontally only
jQuery.fn.centerHor = function (pos) {
this.css("position", pos);
this.css("left", ($(window).width() / 2) - (this.outerWidth() / 2));
return this;
}
// Center it vertically only
jQuery.fn.centerVer = function (pos) {
this.css("position", pos);
this.css("top", ($(window).height() / 2) - (this.outerHeight() / 2));
return this;
}
In my <head>:
<script src="scripts/center.js"></script>
Examples of usage:
$("#example1").centerHor("absolute")
$("#example2").centerHor("fixed")
$("#example3").centerVer("absolute")
$("#example4").centerVer("fixed")
$("#example5").center("absolute")
$("#example6").center("fixed")
It works with any positioning type, and can be used throughout your entire site easily, as well as easily portable to any other site you create. No more annoying workarounds for centering something properly.
Hope this is useful for someone out there! Enjoy.

Lot's of ways to do this. My object is kept hidden with display:none just inside the BODY tag so that positioning is relative to the BODY. After using $("#object_id").show(), I call $("#object_id").center()
I use position:absolute because it is possible, especially on a small mobile device, that the modal window is larger than the device window, in which case some of the modal content could be inaccessible if positioning was fixed.
Here's my flavor based on other's answers and my specific needs:
$.fn.center = function () {
this.css("position","absolute");
//use % so that modal window will adjust with browser resizing
this.css("top","50%");
this.css("left","50%");
//use negative margin to center
this.css("margin-left",(-1*this.outerWidth()/2)+($(window).scrollLeft())+"px");
this.css("margin-top",(-1*this.outerHeight()/2)+($(window).scrollTop())+"px");
//catch cases where object would be offscreen
if(this.offset().top<0)this.css({"top":"5px","margin-top":"0"});
if(this.offset().left<0)this.css({"left":"5px","margin-left":"0"});
return this;
};

You could use the CSS translate property:
position: absolute;
transform: translate(-50%, -50%);
Read this post for more details.

Normally, I would do this with CSS only... but since you asked you a way to do this with jQuery...
The following code centers a div both horizontally and vertically inside its container :
$("#target").addClass("centered-content")
.wrap("<div class='center-outer-container'></div>")
.wrap("<div class='center-inner-container'></div>");
body {
margin : 0;
background: #ccc;
}
.center-outer-container {
position : absolute;
display: table;
width: 100%;
height: 100%;
}
.center-inner-container {
display: table-cell;
vertical-align: middle;
text-align: center;
}
.centered-content {
display: inline-block;
text-align: left;
background: #fff;
padding : 20px;
border : 1px solid #000;
}
<script type="text/javascript" src="https://code.jquery.com/jquery-1.12.1.min.js"></script>
<div id="target">Center this!</div>
(see also this Fiddle)

Just say:
$("#divID").html($('').html($("#divID").html()));

It can be done with only CSS. But they asked with jQuery or JavaScript
Here, use CSS Flex box property to align the div center.
body.center{
display:flex;
align-items:center; // Vertical alignment
justify-content:center; // Horizontal alignment
}
align-items:center; - used to align vertically.
justify-content:center; - used to align horizontally.
document.querySelector("body").classList.add("center");
body {
margin : 0;
height:100vh;
width:100%;
background: #ccc;
}
#main{
background:#00cc00;
width:100px;
height:100px;
}
body.center{
display:flex;
align-items:center;
justify-content:center;
}
<body>
<div id="main"></div>
</body>

I used this to put the UL in the middle position.
cadasWidth = $('.card-dashboard').innerWidth();
cadasWidthCenter = cadasWidth/2;
ulmenuWidth = $('.card-dashboard ul#menu').outerWidth();
ulmenuWidthCenter = ulmenuWidth/2;
ulmenuStart = cadasWidthCenter - ulmenuWidthCenter;
$('.card-dashboard ul#menu').css({
'left' : ulmenuStart,
'position' : 'relative'
});

Why you don't use CSS for centering a div?
#timer_wrap{
position: fixed;
left: 50%;
top: 50%;
}