16f6c0aecf
Inline adoc files when they are included exactly once. Also fix language tags because this inlining gives us better information on what language the code is written in.
54 lines
1.8 KiB
Plaintext
54 lines
1.8 KiB
Plaintext
== Why is this an issue?
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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.
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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.
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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++``.
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=== Noncompliant code example
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[source,javascript]
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----
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x = 42;
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y = x.length; // Noncompliant, Number type doesn't have "length" property
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----
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=== Exceptions
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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:
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* ``++camelize++``
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* ``++capitalize++``
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* ``++classify++``
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* ``++dasherize++``
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* ``++decamelize++``
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* ``++fmt++``
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* ``++loc++``
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* ``++underscore++``
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* ``++w++``
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ifdef::env-github,rspecator-view[]
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'''
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== Comments And Links
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(visible only on this page)
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=== on 1 Nov 2019, 17:34:52 Elena Vilchik wrote:
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See \https://github.com/SonarSource/SonarJS/issues/1698
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=== on 21 Oct 2020, 16:44:43 Guillaume Dequenne wrote:
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Dropping this rule as it has low value. See:
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https://github.com/SonarSource/SonarJS/issues/2208
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https://github.com/SonarSource/SonarJS/issues/1698
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endif::env-github,rspecator-view[]
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