== Why is this an issue?

When either the equality operator in a test for ``++null++`` or ``++undefined++``, or the logical operator that follows it is reversed, the code has the appearance of safely null-testing the object before dereferencing it. Unfortunately the effect is just the opposite - the object is null-tested and then dereferenced only if it is ``++null++``/``++undefined++``, leading to a guaranteed ``++TypeError++``.

=== Noncompliant code example

[source,javascript]
----
if (str == null && str.length == 0) {
  console.log("String is empty");
}

if (str == undefined && str.length == 0) {
  console.log("String is empty");
}

if (str != null || str.length > 0) {
  console.log("String is not empty");
}

if (str != undefined || str.length > 0) {
  console.log("String is not empty");
}
----

=== Compliant solution

[source,javascript]
----
if (str != null && str.length == 0) {
  console.log("String is empty");
}

if (str != undefined && str.length == 0) {
  console.log("String is empty");
}

if (str == null || str.length > 0) {
  console.log("String is not empty");
}

if (str == undefined || str.length > 0) {
  console.log("String is not empty");
}
----

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

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

include::../message.adoc[]

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

=== on 10 Mar 2015, 14:56:30 Ann Campbell wrote:
submitted for your approval [~linda.martin]

=== on 10 Mar 2015, 15:14:19 Linda Martin wrote:
Perfect !

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

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