Why does this not work - very stuck, if else Options

[Shona]

Esentially it checks if the first numerical input or the second input is a number, if not alert if a good number then output it

---

if (((isNaN(first) || (isNaN(second)))
{
Alert("invalid Number entered")
}
else
{
answer=eval(txtanswer);
document.form1.textarea2.value=txtanswer+ "=" +answer;
}

[Brian Chandler]

if (((isNaN(first) || (isNaN(second)))

The brackets don't seem to match!

if (((isNaN(first) || (isNaN(second)))
if (((isNaN() || (isNaN()))
if (((isNaN || (isNaN))
if (((isNaN || ())
if ((()
if ((
!