Get HTML5 data attributes with no type coercion

jquery.readdataattr.js

/**
 * jQuery.readDataAttr
 *
 * Gets html5 data attributes without type coercion.
 * If called with no parameters, returns an object with all
 * current data-* values.
 *
 * @param {String} [key] Optional; if set, return only this
 *    value
 * @return {*} Return either all values, or the value at key
 */
(function (window, $) {

    "use strict";

    var slice = Array.prototype.slice;
    var cache = {};
    var uuid = 0;
    var expando = "jQueryReadDataAttr" + (+new Date());
    var dataTest = /^data-/;

    var readDataAttr = function (elem) {
            var id = elem[expando];
            var data = cache[id];
            var attrs, attr, i, l, key;

            if (!$.isPlainObject(data)) {
                attrs = slice.call(elem.attributes);
                data = {};

                for (i = 0, l = attrs.length; i < l; i++) {
                    attr = attrs[i];

                    if (dataTest.test(attr.name)) {
                        key = attr.name.replace(dataTest, "");
                        key = $.camelCase(key);
                        data[key] = attr.nodeValue;
                    }
                }

                id = uuid++;
                cache[id] = data;
                elem[expando] = id;
            }

            return data;
        };

    $.fn.readDataAttr = function (key) {
        var elem = $(this).get(0);
        var data = readDataAttr(elem);

        if (typeof key !== "undefined") {
            key = $.camelCase(key);
            data = data[key];
        }

        return data;
    };

    $.readDataAttr = function (elem, key) {
        return $(elem).readDataAttr(key);
    };

}(window, jQuery));