如何使用jQuery找到最高的z-index

position: static

var index_highest = 0;   
// more effective to have a class for the div you want to search and 
// pass that to your selector
$(\"#layer-1,#layer-2,#layer-3,#layer-4\").each(function() {
    // always use a radix when using parseInt
    var index_current = parseInt($(this).css(\"zIndex\"), 10);
    if(index_current > index_highest) {
        index_highest = index_current;
    }
});

div

var getMaxZ = function(selector){
    return Math.max.apply(null, $(selector).map(function(){
        var z;
        return isNaN(z = parseInt($(this).css(\"z-index\"), 10)) ? 0 : z;
    }));
};

getMaxZ($(\"#layer-1,#layer-2,#layer-3,#layer-4\"));

jQuery.fn.extend({
    getMaxZ : function(){
        return Math.max.apply(null, jQuery(this).map(function(){
            var z;
            return isNaN(z = parseInt(jQuery(this).css(\"z-index\"), 10)) ? 0 : z;
        }));
    }
});

$(\"#layer-1,#layer-2,#layer-3,#layer-4\").getMaxZ();

$.topZIndex(\"div\");

var index_highest = 0;
$(\'div\').each(function(){
    var index_current = parseInt($(this).css(\"z-index\"), 10);
    if(index_current > index_highest) {
        index_highest = index_current;
    }
}); 

$(document).ready(function() {
    var array = [];
    $(\"div\").each(function() {
        array.push($(this).css(\"z-index\"));
    });
    var index_highest = Math.max.apply(Math, array);
    alert(index_highest);
});

$.map

var $divs = $(\'div\'),
    mapper = function (elem) {
        return parseFloat($(elem).css(\'zIndex\'));
    },
    indices = $.map($divs, mapper);

indices

Math.max

var highest = Math.max.apply(whatevs, indices);

(function ($) {
  $.fn.zIndex = function (zIndex) {
      if (zIndex !== undefined) {
        return this.css(\"zIndex\", zIndex);
      }

      if (this.length) {
        var elem = $(this[ 0 ]), position, value;
        while (elem.length && elem[ 0 ] !== document) {
          // Ignore z-index if position is set to a value where z-index is ignored by the browser
          // This makes behavior of this function consistent across browsers
          // WebKit always returns auto if the element is positioned
          position = elem.css(\"position\");
          if (position === \"absolute\" || position === \"relative\" || position === \"fixed\") {
            // IE returns 0 when zIndex is not specified
            // other browsers return a string
            // we ignore the case of nested elements with an explicit value of 0
            // <div style=\"z-index: -10;\"><div style=\"z-index: 0;\"></div></div>
            value = parseInt(elem.css(\"zIndex\"), 10);
            if (!isNaN(value) && value !== 0) {
              return value;
            }
          }
          elem = elem.parent();
        }
      }

      return 0;
    }
})(jQuery);

function getZindex (id) {

     var _l = [];
     $(id).each(function (e) {
         // skip if z-index isn\'t set 
         if ( $(this).css(\'z-index\') == \'auto\' ) {
              return true
         }
         _l.push({ id: $(this), zindex: $(this).css(\'z-index\') });
     });
     _l.sort(function(a, b) { return a.zindex - b.zindex });
     return _l;
}

// You\'ll need to add a class \'layer\' to each of your layer
var _zindexes = getZindex(\'.layer\');
var _length = _zindexes.length;

// Highest z-index is simply the last element in the array
var _highest = _zindexes[_length - 1].zindex

// Lowest z-index is simply the first element in the array
var _lowest = _zindex[0].zindex;

alert(_highest);
alert(_lowest);

function getHighIndex (selector) {
    // No granularity by default; look at everything
    if (!selector) { selector = \'*\' };

    var elements = document.querySelectorAll(selector) ||
                   oXmlDom.documentElement.selectNodes(selector),
        i = 0,
        e, s,
        max = elements.length,
        found = [];

    for (; i < max; i += 1) {
        e = window.getComputedStyle(elements[i], null).zIndex || elements[i].currentStyle.zIndex;
        s = window.getComputedStyle(elements[i], null).position || elements[i].currentStyle.position;

        // Statically positioned elements are not affected by zIndex
        if (e && s !== \"static\") {
          found.push(parseInt(e, 10));
        }
    }

    return found.length ? Math.max.apply(null, found) : 0;
}

$(\'div[id^=layer-]\').css(\'z-index\', 0);
$(this).css(\'z-index\', 1000);