Function dataAttr

2.0.3/Data.js:379–406

* 处理HTML5的data-*属性 * 逻辑结构更为清晰 * @param {[type]} elem [description] * @param {[type]} key [description] * @param {[type]} data [description] * @return {[type]} [description]

(elem, key, data)

     * @return {[type]}      [description]
     */
    function dataAttr(elem, key, data) {
        var name;

        // If nothing was found internally, try to fetch any
        // data from the HTML5 data-* attribute
        if (data === undefined && elem.nodeType === 1) {
            name = "data-" + key.replace(rmultiDash, "-$1").toLowerCase();
            data = elem.getAttribute(name);

            if (typeof data === "string") {
                try {
                    data = data === "true" ? true :
                        data === "false" ? false :
                        data === "null" ? null :
                    // Only convert to a number if it doesn't change the string
                    +data + "" === data ? +data :
                        rbrace.test(data) ? JSON.parse(data) :
                        data;
                } catch (e) {}

                // Make sure we set the data so it isn't changed later
                data_user.set(elem, key, data);
            } else {
                data = undefined;
            }
        }
        return data;
    }