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.
66 lines
2.2 KiB
Plaintext
66 lines
2.2 KiB
Plaintext
== Why is this an issue?
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The result of an expression with an arithmetic operator ``/, *, %, {plus}{plus}, --, -, {plus}=, -=, *=, /=, %=, {plus}`` or unary operator ``+++, -++`` when at least one operand is ``++Object++`` or ``++Undefined++`` will be always a ``++NaN++`` (Not a Number).
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=== Noncompliant code example
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[source,javascript]
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----
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x = [1, 2];
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var y = x / 4; //Noncompliant
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----
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=== Exceptions
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* ``++Date++`` operands: they are implicitly converted to numbers.
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* The binary ``+`` operator with ``++Object++`` operand (concatenation).
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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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=== Message
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Change the expression which uses this operand so that it can't evaluate to "NaN" (Not a Number).
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=== Highlighting
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Primary: operand triggering the rule
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Secondary: operator
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Secondary: second operand
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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 18 Oct 2016, 10:47:28 Pierre-Yves Nicolas wrote:
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We may raise false positives when one of the operands is an ``++Object++``. An ``++Object++`` which wraps some kind of number may have a valid ``++valueOf++`` method: see https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Object/valueOf#Examples[an example].
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If we see that we raise too many false positives, we can:
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* raise an issue only on some kinds of ``++Object++`` for which we know that there is a problem: ``++Array++``, ``++Date++``, ``++Function++``, ``++Regexp++``
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* keep the same exception on ``+`` for these kinds of operand
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=== on 25 Oct 2016, 15:44:36 Pierre-Yves Nicolas wrote:
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\[~jeanchristophe.collet] I think that the message should always be "imperative", e.g. "Remove...", "Change...".
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=== on 25 Oct 2016, 15:47:45 Pierre-Yves Nicolas wrote:
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\[~jeanchristophe.collet] What about ``+++=++``?
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=== on 25 Oct 2016, 16:01:10 Jean-Christophe Collet wrote:
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I addressed both comments above.
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=== on 31 Oct 2016, 12:24:53 Pierre-Yves Nicolas wrote:
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More detailed message: "The value of this operand is (undefined|an object) on at least one path of execution. Refactor the code to avoid having NaN ("Not a Number") as the result of the parent expression."
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endif::env-github,rspecator-view[]
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