Facebook webpage title renamer

/* FACEBOOK GROUPS TITLE RENAMER */
setTimeout(reTitle, 3000);

$(document).keyup(function(e) {
    reTitle();
});

function reTitle() {
    var titletext = prepare();
    if (titletext) {
        var pagetitle = $('title');
        var title = pagetitle.innerText;
        if (title != titletext)
            changeTitle(titletext);
    }
}

function changeTitle(titletext) {
    var pagetitle = $('title');
    pagetitle.html(titletext);
}

function prepare(){
    var groupname = $('#seo_h1_tag')[0];
    var membername = $('h5[id^="js_"]')[0];
    var postcontent = $('#pagelet_group_mall [data-testid="post_message"]')[0];
    if (groupname)
        groupname = groupname.innerText;
    if (membername)
        membername = membername.innerText;
    if (postcontent) {
        postcontent = postcontent.innerText;
        var firstLine = postcontent.split('\n')[0];
        postcontent = firstLine;
        if (postcontent.length > 48)
            postcontent = postcontent.substring(0,48) + "...";
    }

    var s = " - ";
    var title = '';
    if (membername && postcontent && groupname)
        title = membername + s +  postcontent + s + groupname;
    return title;
};