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Javascript Number - NaN
Description:
Unquoted literal constant NaN is a special value representing Not-a-Number. Since NaN always compares unequal to any number, including NaN, it is usually used to indicate an error condition for a function that should return a valid number.
Note: Use the isNaN() global function to see if a value is an NaN value.
Syntax:
You can access this property using the following syntax:
Example:
Here dayOfMonth is assigned NaN if it is greater than 31, and a message is displayed indicating the valid range:
<html>
<head>
<script type="text/javascript">
<!--
function showValue()
{
var dayOfMonth = 50;
if (dayOfMonth < 1 || dayOfMonth > 31)
{
dayOfMonth = Number.NaN
alert("Day of Month must be between 1 and 31.")
}
alert("Value of dayOfMonth : " + dayOfMonth );
}
//-->
</script>
</head>
<body>
<p>Click the following to see the result:</p>
<form>
<input type="button" value="Click Me" onclick="showValue();" />
</form>
</body>
</html>
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This will produce following result:
Day of Month must be between 1 and 31.
Value of dayOfMonth : NaN
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To understand it in better way you can Try it yourself.
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