ValueChanging Property (TextEditorClientEvents)

// The client event 'ValueChanging' takes two parameters sender and e
// sender  is the object which is raising the event
// e is the TextEditorValueChangingEventArgs

//ID of the editor raising the event is "Editor"

function Editor_ValueChanging(sender, e) {

    //Gets the old value in the editor
    var oldValue = e.get_oldValue();

    //Gets the new value in the editor
    var newValue = e.get_value();

    if (!confirm("Are you sure you want to change the value '" + oldValue + "' to '" + newValue + "?"))

        //Cancels the ValueChanging event
        e.set_cancel(true);

}