这样写:
<HTML>
<HEAD>
<script>
function luru(a){
if(event.keyCode=="112")
a.value="优秀";
if(event.keyCode=="113")
a.value="良好";
if(event.keyCode=="114")
a.value="及格";
}</script></HEAD>
<BODY>
<form>
按F1:<input type=text onKeydown="luru(this)"><br>
按F2:<input type=text onKeydown="luru(this)"><br>
按F3:<input type=text onKeydown="luru(this)">
</form>
</BODY>
</HTML>
<HTML>
<HEAD>
<script>
function luru(a){
if(event.keyCode=="112")
a.value="优秀";
if(event.keyCode=="113")
a.value="良好";
if(event.keyCode=="114")
a.value="及格";
}</script></HEAD>
<BODY>
<form>
按F1:<input type=text onKeydown="luru(this)"><br>
按F2:<input type=text onKeydown="luru(this)"><br>
按F3:<input type=text onKeydown="luru(this)">
</form>
</BODY>
</HTML>
<HEAD>
<script>
function keydown(a,evt)
{
if(keyCode=="13")
return tabOnEnter (event.field, evt)
if(keyCode=="113")
return luru(a)
}
function luru(a){
if(event.keyCode=="112")
a.value="优秀";
if(event.keyCode=="113")
a.value="良好";
if(event.keyCode=="114")
a.value="及格";
}
function getNextElement (field) {
var form = field.form;
for (var e = 0; e < form.elements.length; e++)
if (field == form.elements[e])
break;
return form.elements[++e % form.elements.length];
}
function tabOnEnter (field, evt) {
var keyCode = document.layers ? evt.which : document.all ?
evt.keyCode : evt.keyCode;
if (keyCode != 13)
return true;
else {
getNextElement(field).focus();
return false;
}
}</script></HEAD>
<BODY>
<FORM NAME="aForm" ONSUBMIT="if (!this.submitted) return false; else return true;">
<input type=text onKeydown="keydown(this,event)"><br>
<input type=text onKeydown="keydown(this,event)"><br>
<input type=text onKeydown="keydown(this,event)">
<INPUT TYPE="submit" ONCLICK="this.form.submitted = true;">
</form>
</BODY>
</HTML>