ComparisonWithNaN.qhelp

<!DOCTYPE qhelp PUBLIC
  "-//Semmle//qhelp//EN"
  "qhelp.dtd">
<qhelp>
<overview>
<p>
Arithmetic comparisons with the special not-a-number value <code>NaN</code> are useless: nothing is considered
to be equal to <code>NaN</code>, not even <code>NaN</code> itself, and similarly nothing is considered greater
or less than <code>NaN</code>.
</p>

</overview>
<recommendation>

<p>
Use the <code>isNaN</code> function from the standard library to determine whether a given value is <code>NaN</code>.
</p>

</recommendation>
<example>

<p>
Instead of <code>x === NaN</code>, use <code>isNaN(x)</code>.
</p>

</example>
<references>


<li>Arvind Kumar: <a href="http://www.devarticles.in/javascript/javascript-common-mistake-of-comparing-variable-with-nan-and-not-with-isnan/">Javascript common mistake of comparing with NaN and not with isNaN</a>.</li>
<li>Mozilla Developer Network: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/NaN">NaN</a>.</li>


</references>
</qhelp>