<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
<HEAD> <script language=javascript>
function a(){
var t1=document.all.t1.value;
var t2=document.all.t2.value;
var t3=document.all.t3;
if(t1!="" && t2!=""){
try{
t3.value=parseFloat(t1)+parseFloat(t2);
}catch(E){
t3.value="error";
}
}
}
</script>
</HEAD> <BODY>
<body>
<input type=text name=t1 onchange="a();"><br>
<input type=text name=t2 onchange="a();"><br>
<input type=text name=t3 value="">
</body>
</BODY>
</HTML>
<HTML>
<HEAD> <script language=javascript>
function a(){
var t1=document.all.t1.value;
var t2=document.all.t2.value;
var t3=document.all.t3;
if(t1!="" && t2!=""){
try{
t3.value=parseFloat(t1)+parseFloat(t2);
}catch(E){
t3.value="error";
}
}
}
</script>
</HEAD> <BODY>
<body>
<input type=text name=t1 onchange="a();"><br>
<input type=text name=t2 onchange="a();"><br>
<input type=text name=t3 value="">
</body>
</BODY>
</HTML>
<HTML>
<HEAD> <script language=javascript>
function a(){
var t1=document.all.t1.value;
var t2=document.all.t2.value;
var t3=document.all.t3;
var a=getData(t1);
var b=getData(t2);
//alert(a+":"+b);
t3.value=a+b;
}
function getData(o){
if(o=="" ){
return 0;
}
return parseFloat(o);
}
</script>
</HEAD> <BODY>
<body>
<input type=text name=t1 onchange="a();"><br/>
<input type=text name=t2 onchange="a();"><br/>
<input type=text name=t3 value="">
</body>
</BODY>
</HTML>