获取整个document最大可用的 zIndex

jetbrick.zIndex.js

(function(window, jetbrick) {
    /**
     * 获取整个document最大可用的 zIndex
     *
     * @returns {Number}
     */
    jetbrick.zIndex = function() {
        var nodes = window.document.getElementsByTagName("*");
        var max = 0;
        for (var i = 0; i < nodes.length; i++) {
            var node = nodes[i];
            var zIndex;
            if (window.getComputedStyle) {
                var styles = window.getComputedStyle(node, null);
                zIndex = styles.getPropertyValue("zIndex") || styles.zIndex;
            } else if (node.currentStyle) {
                zIndex = node.currentStyle.zIndex;
            } else {
                zIndex = node.style.zIndex;
            }
            if (zIndex !== "") {
                zIndex = (+zIndex) || 0;
                if (max < zIndex) {
                    max = zIndex;
                }
            }
        }
        return max + 1;
    };

})(window, window.jetbrick || (window.jetbrick = {}));