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JavaScript isNaN() Function

Definition and Usage

The isNaN() function is used to check if a value is not a number.

Syntax

isNaN(number)

Parameter Description
number Required. The value to be tested


Example

In this example we use isNaN() to check some values:

<script type="text/javascript">
document.write(isNaN(123)+ "<br />");
document.write(isNaN(-1.23)+ "<br />");
document.write(isNaN(5-2)+ "<br />");
document.write(isNaN(0)+ "<br />");
document.write(isNaN("Hello")+ "<br />");
document.write(isNaN("2005/12/12")+ "<br />");
</script>

The output of the code above will be:

false
false
false
false
true
true
JavaScript isNaN() Function Reviewed by 1000sourcecodes on 03:33 Rating: 5
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