我在扩展@TonyL给出的精彩答案。我添加了Math.abs()来包装值，而且我还考虑到jQuery可能处于“无冲突”模式，例如在WordPress中。

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.

我做的另一件事是通过缓存$(window)对象来加快速度，这样我就减少了额外的DOM遍历，并且我使用了集群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;
}

要使用，你可以这样做:

jQuery(document).ready(function($){
  $('#myelem').center();
});

不需要jquery

我用这个来居中Div元素。 Css样式,

.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;
}

开放的元素

$(document).ready(function(){
    $(".open").click(function(e){
      $(".black_overlay").fadeIn(200);
    });

});

我会推荐jQueryUI位置实用工具

$('your-selector').position({
    of: $(window)
});

这给了你更多的可能性，而不仅仅是定心…

这是我的尝试。我最终在我的Lightbox克隆版本中使用了它。这种解决方案的主要优点是，即使窗口大小被调整，元素也会自动保持居中，这是这种用法的理想选择。

$.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;
}

我在扩展@TonyL给出的精彩答案。我添加了Math.abs()来包装值，而且我还考虑到jQuery可能处于“无冲突”模式，例如在WordPress中。

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.

我做的另一件事是通过缓存$(window)对象来加快速度，这样我就减少了额外的DOM遍历，并且我使用了集群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;
}

要使用，你可以这样做:

jQuery(document).ready(function($){
  $('#myelem').center();
});

我喜欢添加函数到jQuery，所以这个函数会有帮助:

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;
}

现在我们可以写成:

$(element).center();

演示:小提琴(添加参数)