获取触发事件的元素id

I have searched google but it seems no one has come across this issue. I have an keypress event set on a form. I am disabling the enter key(until all required fields are filled in) and trying to enable the + key to be used to move to the next available input area on the form. My form is highly dynamic other than the couple required fields so I won't know what field element someone is on when they press the + key. I just need to move to the next form input element. Here is my code so far. The disabling of the enter key works fine. I just need to find a way of moving the focus from the current input field to the next available input field. So if you know of a better way please let me know.I have searched google but it seems no one has