(function () {
    var userAgent = navigator.userAgent.toLowerCase();
    var browser = {
        safari: /webkit/.test(userAgent),
        opera: /opera/.test(userAgent),
        msie: /msie/.test(userAgent) && !/opera/.test(userAgent),
        mozilla: /mozilla/.test(userAgent) && !/(compatible|webkit)/.test(userAgent)
    };

    var observe = function(obj, evt, callback) {
        try {
            obj.addEventListener(evt, callback, false);
        } catch (e) {
            obj.attachEvent('on' + evt, callback)
        }
    };

    observe(window, 'load', function() {
        var url = 'http://www.ehikkoshitai.com';
        var title = '引越し隊.com';

        var anchor = document.createElement('a');
        anchor.href = '#';
        if (browser.msie) {
            observe(anchor, 'click', function() {
                window.external.AddFavorite(url, title);
            });
        } else if (browser.mozilla) {
            observe(anchor, 'click', function() {
                window.sidebar.addPanel(title, url, '');
            });
        } else if (browser.opera) {
            anchor.href = url;
            anchor.rel = 'sidebar';
            anchor.title = title;
        } else {
            return;
        }

        anchor.innerHTML = 'お気に入りに追加';
        document.getElementById('add_to_favorites').appendChild(anchor);
    });
})();