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.
77 lines
1.8 KiB
Plaintext
77 lines
1.8 KiB
Plaintext
== Why is this an issue?
|
|
|
|
In a Zen-like manner, ``++NaN++`` isn't equal to anything, even itself. So comparisons (``++>, <, >=, <=++``) where one operand is ``++NaN++`` or evaluates to ``++NaN++`` always return ``++false++``. Specifically, ``++undefined++`` and objects that cannot be converted to numbers evaluate to ``++NaN++`` when used in numerical comparisons.
|
|
|
|
|
|
This rule raises an issue when there is at least one path through the code where one of the operands to a comparison is ``++NaN++``, ``++undefined++`` or an ``++Object++`` which cannot be converted to a number.
|
|
|
|
|
|
=== Noncompliant code example
|
|
|
|
[source,javascript]
|
|
----
|
|
var x; // x is currently "undefined"
|
|
if (someCondition()) {
|
|
x = 42;
|
|
}
|
|
|
|
if (42 > x) { // Noncompliant; "x" might still be "undefined"
|
|
doSomething();
|
|
}
|
|
|
|
var obj = {prop: 42};
|
|
if (obj > 24) { // Noncompliant
|
|
doSomething();
|
|
}
|
|
----
|
|
|
|
|
|
=== Compliant solution
|
|
|
|
[source,javascript]
|
|
----
|
|
var x;
|
|
if (someCondition()) {
|
|
x = 42;
|
|
} else {
|
|
x = foo();
|
|
}
|
|
|
|
if (42 > x) {
|
|
doSomething();
|
|
}
|
|
|
|
var obj = {prop: 42};
|
|
if (obj.prop > 24) {
|
|
doSomething();
|
|
}
|
|
----
|
|
|
|
|
|
ifdef::env-github,rspecator-view[]
|
|
|
|
'''
|
|
== Implementation Specification
|
|
(visible only on this page)
|
|
|
|
=== Message
|
|
|
|
Re-evaluate the data flow; this operand of a numeric comparison could be {"undefined"|an Object}.
|
|
|
|
|
|
=== Highlighting
|
|
|
|
Primary: Expression
|
|
|
|
Secondary: Path that puts comparison var in bad state
|
|
|
|
|
|
'''
|
|
== Comments And Links
|
|
(visible only on this page)
|
|
|
|
=== on 18 Oct 2016, 10:54:41 Pierre-Yves Nicolas wrote:
|
|
Similarly to RSPEC-3757, we may raise a false positive if the object has a ``++valueOf++`` method (which is the case for ``++Date++`` which we already exclude). We will refine that if the currently described behavior raises too many false positives.
|
|
|
|
endif::env-github,rspecator-view[]
|