JavaScript Global method: isNaN()
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The JavaScript
Global
isNaN() method returns true if the value equates to NaN
(after initial conversion to a Number) otherwise returns false.
It
has the following syntax with the following parameters:
isNaN(x)
|
Parameter
|
Required / Optional
|
Description
|
|
x
|
Required
|
Input parameter
|
The Number.isNaN
method is subtly different to the global isNaN
function. The latter coerces a value to a number before testing it, whilst the
former does not. So, Number.isNaN("NaN")
returns false, whilst isNaN("NaN") returns true.
EXAMPLE:
HTML USED IN THIS EXAMPLE:
<!DOCTYPE html>
<html> <!-- Copyright (c) Nematrian Limited 2018 -->
<head>
<style>
table,th,tr,td {border: 1px solid black; border-collapse: collapse;}
</style>
</head>
<body>
<table>
<tr>
<th>Example</th>
<th>Resulting value of <code>x</code></th>
</tr>
<tr>
<td><code id="Example"></code></td>
<td><code id="Result"></code></td>
</tr>
<tr>
<td><code id="Example2"></code></td>
<td><code id="Result2"></code></td>
</tr>
</table>
<script>
document.getElementById("Example").innerHTML =
'var x = isNaN(0/0);';
document.getElementById("Result").innerHTML
= isNaN(0/0);
document.getElementById("Example2").innerHTML =
'var x = isNaN(0/1);';
document.getElementById("Result2").innerHTML
= isNaN(0/1);
</script>
</body>
</html>
|
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