<form name="form1" method="post" action="">
数量: <input type="text" name="sl" onKeyup="accu()">
均价: <input type="text" name="jj" onKeyup="accu()">
总价: <input type="text" name="zj" onKeyup="accu()">
<script language="JavaScript">
function accu(){
var s=document.form1.sl.value;
var j=document.form1.jj.value;
var z=document.form1.zj.value;
if(s,j){
document.form1.zj.value=s*j;
}
else if(s,z){
document.form1.jj.value=z/s;
}
}
</script>
</form>