gm-setMicroformats.user.js

// ==UserScript==
// @name           setMicroformats
// @namespace      http://webtech-walker.com/
// @description    set class by wedata
// @include        http://*
// @include        https://*
// ==/UserScript==

(function() {
    var addClass = function(selector, className) {
        var elems = Array.prototype.slice.call(document.querySelectorAll(selector));
        elems.forEach(function(elem) {
            var baseClass = elem.getAttribute('class');
            var setClass = baseClass ? ' ' + baseClass : '';
            setClass += className;
            elem.setAttribute('class', setClass);
        });
    }

    GM_xmlhttpRequest({
        method: 'GET',
        url:    'http://wedata.net/databases/mf-test/items.json',
        onload: function(res) {
            info = eval(res.responseText).map(function(i) { return i.data });
            info.forEach(function(data) {
                var regex = new RegExp(data.url);
                if ( regex.test(location.href) ) {
                    var selectors = eval('[' + data.selector + ']');
                    var classes = eval('[' + data.class + ']');
                    selectors.forEach(function(selector, i) {
                        addClass(selector, classes[i]);
                    });
                }
            });
        },
    });
})();