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.
47 lines
1.3 KiB
Plaintext
47 lines
1.3 KiB
Plaintext
== Why is this an issue?
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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.
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=== Noncompliant code example
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[source,javascript]
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----
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if (x === undefined) {
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console.log(x.bar); // Noncompliant; TypeError will be thrown
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}
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----
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include::../see.adoc[]
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ifdef::env-github,rspecator-view[]
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'''
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== Implementation Specification
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(visible only on this page)
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include::../message.adoc[]
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include::../highlighting.adoc[]
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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 15 Mar 2016, 09:45:14 Pierre-Yves Nicolas wrote:
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Useful links:
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* \https://javascriptweblog.wordpress.com/2010/08/16/understanding-undefined-and-preventing-referenceerrors/
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* \https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/undefined
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We could make this rule also cover invalid function calls, e.g.:
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----
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var x = 42;
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x(); // Noncompliant: TypeError will be thrown
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----
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However, there may be some overlap with RSPEC-2999.
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include::../comments-and-links.adoc[]
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endif::env-github,rspecator-view[]
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