jquery div 居中技巧应用介绍

very short version:
[html]

$('#myDiv').css({top:'50%',left:'50%',margin:'-'+($('#myDiv').height() / 2)+'px 0 0 -'+($('#myDiv').width() / 2)+'px'}); 
$('#myDiv').css({top:'50%',left:'50%',margin:'-'+($('#myDiv').height() / 2)+'px 0 0 -'+($('#myDiv').width() / 2)+'px'});

short version:
[html]

(function($){ 
$.fn.extend({ 
center: function () { 
return this.each(function() { 
var top = ($(window).height() - $(this).outerHeight()) / 2; 
var left = ($(window).width() - $(this).outerWidth()) / 2; 
$(this).css({position:'absolute', margin:0, top: (top > 0 ? top : 0)+'px', left: (left > 0 ? left : 0)+'px'}); 
}); 
} 
}); 
})(jQuery); 
(function($){ 
$.fn.extend({ 
center: function () { 
return this.each(function() { 
var top = ($(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();

[javascript]

(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 $(this); 
}); 
} 
}); 
})(jQuery); 
[code] 
(function($){ 
$.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);

PLUGIN VERSION
[javascript]

(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);

(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}); 
}); 
);

观此人JS代码，让人叹为观止。
简洁明了。却又举一反三。