function copyToClipboard(text) {
    if (window.clprdData) { // Internet Explorer
        window.clprdData.setData("Text", text);
    } else {
        unsafeWindow.netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect");
        const clprdHelper = Components.classes["@mozilla.org/widget/clipboardhelper;1"].getService(Components.interfaces.nsIClprdHelper);
        clprdHelper.copyString(text);
    }
}

How I can filter an array of text to including only letters and symbols???