rspec/rules/S2259/javascript/rule.adoc

When a variable is assigned an ``undefined`` or ``null`` value, it has no properties. Trying to access properties of such a variable anyway results in a ``TypeError``, causing abrupt termination of the script if the error is not caught in a ``catch`` block. But instead of ``catch``-ing this condition, it is best to avoid it altogether.

== Noncompliant Code Example

----
if (x === undefined) {
  console.log(x.length); // Noncompliant; TypeError will be thrown
}
----

include::../see.adoc[]