Reading a non-existent property on an object always returns ``++undefined++``. Doing so is usually an error; either in the name of the property or the type of the variable being accessed.


If an attempt is made to access properties of a primitive, the primitive is automatically encased in a primitive-wrapper object for the operation. But being "promoted" to an object doesn't mean that the primitive will actually have properties to access. The wrapper object still won't have the non-existent property and ``++undefined++`` will be returned instead. 


This rule raises an issue when an attempt is made to access properties of a primitive. Thus this rule should only be activated when you don't use monkey patching for standard objects, like ``++Number++``, ``++Boolean++`` and ``++String++``. 


== Noncompliant Code Example

----
x = 42;
y = x.length;   // Noncompliant, Number type doesn't have "length" property
----


== Exceptions

The Ember framework introduces a few extensions to ``++String++``. Since it is a widely used package, the following ``++String++`` properties will not trigger this rule even though they are not built-in:

* ``++camelize++``
* ``++capitalize++``
* ``++classify++``
* ``++dasherize++``
* ``++decamelize++``
* ``++fmt++``
* ``++loc++``
* ``++underscore++``
* ``++w++``


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== Comments And Links
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include::comments-and-links.adoc[]
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