function copyToClipboard (copytext) {
const supstr = Components.classes["@mozilla.org/supports-string;1"].
createInstance(Components.interfaces.nsISupportsString);
const transferable = Components.classes["@mozilla.org/widget/transferable;1"].
createInstance(Components.interfaces.nsITransferable);
const iClipboard = Components.interfaces.nsIClipboard;
const clipboard = Components.classes["@mozilla.org/widget/clipboard;1"].
getService(iClipboard);
supstr.data = copytext;
transferable.addDataFlavor("text/unicode");
transferable.setTransferData("text/unicode", supstr, copytext.length * 2);
return clipboard.setData(transferable, null, iClipboard.kGlobalClipboard);
}
copyToClipboard('hogehoge');