ニコニコ動画のwatchページのタブを追加する関数(Firefox依存なし)

nicovideo_createPanel.js

// http://blog.livedoor.jp/eeu/archives/55316335.html
var addClassName = function(el, className) {
    var reg = new RegExp('(^| +)' + className + '($| +)');
    if (!reg.test(el.className))
        el.className += ' ' + className;
};
var removeClassName = function(el, className) {
    var reg = new RegExp('(^| +)' + className + '($| +)');
    el.className = el.className.replace(reg, ' ');
};

function nicovideo_createPanel(id, labelText) {
    var panelID = 'itab_' + id;
    var label = document.createElement('a');
    label.href = '#' + panelID;
    label.innerHTML = '<div>' + labelText + '</div>';
    // remove extra <a>...</a>
    label.firstChild.textContent = labelText;
    document.querySelector('#itab td').appendChild(label);

    var panel = document.createElement('div');
    panel.id = panelID;
    panel.className = 'info';
    document.querySelector('.info_frm').appendChild(panel);

    //unsafeWindow.cont = unsafeWindow.$$('.info_frm .info');
    var act = "in";// unsafeWindow.act
    label.addEventListener('click', function(e) {
        e.preventDefault();
        Array.forEach(document.querySelectorAll('#itab td a'), function(elm) {
            removeClassName(elm, act)
        });

        addClassName(label, act);
        Array.forEach(document.querySelectorAll('.info_frm .info'), function(elm) {
            elm.id === panelID
                    ? addClassName(elm, act)
                    : removeClassName(elm, act)
        });
    }, false);

    return { label: label, panel: panel };
}

sample.js

// ニコニコ大百科という名前のタブを作る (panel.id == nicopedia)
var nicovideo_createPanel_res = nicovideo_createPanel('nicopedia', 'ニコニコ大百科'),
            panel = nicovideo_createPanel_res.panel,
            label = nicovideo_createPanel_res.label;
// タブのパネルに表示する内容を指定する
panel.appendChild(document.createTextNode('hogehoge'));