NaN i udregning
Hvordan undgår jeg NaN i en udregning?jeg har defineret value=\"0\" i inputfelterne, men hvis brugeren deleter \"0\" så der står et blankt felt bliver resultatet NaN.
<HTML>
<HEAD><TITLE></TITLE>
<SCRIPT>
function calculate(sum)
{
document.form1.elements[sum].value =
parseInt(document.form1.x1.value)
+ parseInt(document.form1.x2.value)
+ parseInt(document.form1.x3.value)
}
</SCRIPT>
</HEAD><BODY BGCOLOR=\"#ffffff\" onload=\"calculate\" >
<form name=\"form1\" action=\"\" method=\"post\">
<input type=\"text\" name=\"x1\" size=\"8\" class=\"box\" value=\"0\">
+
<input type=\"text\" name=\"x2\" size=\"8\" class=\"box\" value=\"0\">
+
<input type=\"text\" name=\"x3\" size=\"8\" class=\"box\" value=\"0\">
=
<input type=\"text\" name=\"sum\" size=\"8\" class=\"box\">
<input type=\"button\" value=\"Beregn\" onClick=\"calculate(\'sum\')\" name=\"button\" class=\"box2\">
</form></BODY></HTML>
