== Why is this an issue?

include::../description.adoc[]

=== Noncompliant code example

[source,javascript]
----
var a = NaN;

if (a === NaN) {  // Noncompliant; always false
  console.log("a is not a number");  // this is dead code
}
if (a !== NaN) { // Noncompliant; always true
  console.log("a is not NaN"); // this statement is not necessarily true
}
----


=== Compliant solution

[source,javascript]
----
if (Number.isNaN(a)) { 
  console.log("a is not a number");
}
if (!Number.isNaN(a)) {
  console.log("a is not NaN"); 
}
----


ifdef::env-github,rspecator-view[]

'''
== Implementation Specification
(visible only on this page)

=== Message

Use a test of the format "a [!==|!=|==|===] a" instead.


'''
== Comments And Links
(visible only on this page)

include::../comments-and-links.adoc[]
endif::env-github,rspecator-view[]