怎么在firefox中把enter键转化为tab键

如何在firefox中把enter键转化为tab键?
rt

------解决方案--------------------
<input type= "text " onkeydown= "trans(event); ">

<script language= "Javascript ">
function trans(obj) {
if(obj.keyCode == '13 ') {
obj.keyCode = 8;
}

}