https://www.also.pt/js/jquery-center/0.0/jquery.center.js?v=buildNumber

1$.fn.center = function (options) {
2
3	if(options instanceof jQuery) {
4		inside_el = options;
5		options = null
6	}
7	else inside_el = null;
8
9	options = options || {}
10	options.this = options.this || {}
11	options.inside = options.inside || {}
12
13	if (options.this.h == null) options.this.h = 0.5
14	if (options.this.v == null) options.this.v = 0.5
15
16	options.inside.el = $(options.inside.el || inside_el || this.parent())
17	if (options.inside.h == null) options.inside.h = 0.5
18	if (options.inside.v == null) options.inside.v = 0.5
19
20	if (options.hOffset == null) options.hOffset = 0;
21	if (options.vOffset == null) options.vOffset = 0;
22
23	this.css("position","absolute");
24
25	this.css("left", (options.inside.el.width() * options.inside.h - this.width() * options.this.h + options.hOffset) + "px");
26
27	this.css("top", (options.inside.el.height() * options.inside.v - this.height() * options.this.v + options.vOffset)  + "px");
28
29	return this;
30}