rspec/rules/S1764/javascript/rule.adoc

== Why is this an issue?

include::../description.adoc[]

=== Noncompliant code example

[source,javascript]
----
if (a == b && a == b) { // if the first one is true, the second one is too
  doX();
}
if (a > a) { // always false
  doW();
}

var j = 5 / 5; //always 1
var k = 5 - 5; //always 0
----

=== Exceptions

The specific case of testing one variable against itself is a valid test for ``++NaN++`` and is therefore ignored.

Similarly, left-shifting 1 onto 1 is common in the construction of bit masks, and is ignored.

Moreover comma operator ``++,++`` and ``++instanceof++`` operator are ignored as there are use-cases when there usage is valid.

[source,javascript]
----
if (f !== f) { // test for NaN value
  console.log("f is NaN");
}

var i = 1 << 1; // Compliant
var j = a << a; // Noncompliant
----

include::../see.adoc[]

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

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

include::../message.adoc[]

include::../highlighting.adoc[]

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

include::../comments-and-links.adoc[]

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