Centering a div vertically & horizontally using jQuery

Question

I am using this script to center my div horizontally and vertically.

When the page loads the div gets centered vertically, not horizontally until I resize the brows

Answer 1

use this to center:

$.fn.center = function () {
   this.css("position","absolute");
   this.css("top", ( $(window).height() - this.height() ) / 2  + "px");
   this.css("left", ( $(window).width() - this.width() ) / 2 + "px");
   return this;
}

$('yourElem').center();

Answer 2

Related to your code snippet, you need to set the position first:

$(window).resize(function (){
    var $el = $('.className');
    $el.css('position', 'absolute').css({
        left: ($(window).width() - $el.width()) / 2,
        top: ($(window).height() - $el.height()) / 2
    });
});

Maybe you could set the position attribute via a static CSS style.

Answer 3

I normally use this "technique":

$(function() {
    $('.className').css({
        'position' : 'absolute',
        'left' : '50%',
        'top' : '50%',
        'margin-left' : -$('.className').width()/2,
        'margin-top' : -$('.className').height()/2
    });
});

---

UPDATE:

I'm updating the solution, as suggested by the user Fred K, using .outerWidth() and .outerHeight() to have a more precise centering.

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

Some additional notes from jQuery' documentation (.outerWidth(), .outerHeight()):

• The number returned by dimensions-related APIs, including .outerWidth(), may be fractional in some cases. Code should not assume it is an integer. Also, dimensions may be incorrect when the page is zoomed by the user; browsers do not expose an API to detect this condition.

• The value reported by .outerWidth() is not guaranteed to be accurate when the element's parent is hidden. To get an accurate value, you should show the parent first, before using .outerWidth().

---

UPDATE 2:

A simple update to show how you could use this inside the css() method in case there are more elements with the same class tag with different sizes.

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

Answer 4

based on @dimi's answer, works better with multiple elements

$(".className").each(
    function () {
       $( this ).css("position","absolute");
       $( this ).css("left","50%");
       $( this ).css("margin-left", - $( this ).outerWidth()/2 );
       $( this ).css("top","50%");
       $( this ).css("margin-top", - $( this ).outerHeight()/2 );
       return this;
    }
);

Answer 5

I use this JQuery.center plugin to center my DOM elements. The code will be something like this:

$("#child").center()

The prior code will center relative to its direct parent, if you need to center relative to another parent, it will be:

$("#child").center($("#parent"))

There are customized options, if you need other form of centralization.

Answer 6

Wrap the handler code in a function so you can call that function both on page load as well as handler for $(window).resize()

/* use as handler for resize*/
$(window).resize(adjustLayout);
/* call function in ready handler*/
$(document).ready(function(){
    adjustLayout();
    /* your other page load code here*/
})

function adjustLayout(){
    $('.className').css({
        position:'absolute',
        left: ($(window).width() - $('.className').outerWidth())/2,
        top: ($(window).height() - $('.className').outerHeight())/2
    });

}