rspec/rules/S4043/javascript/rule.adoc

== Why is this an issue?

Many of JavaScript's ``++Array++`` methods return an altered version of the array while leaving the source array intact. ``++reverse++`` and ``++sort++`` do not fall into this category. Instead, they alter the source array _in addition to_ returning the altered version, which is likely not what was intended.


This rule raises an issue when the return values of these methods are assigned, which could lead maintainers to overlook the fact that the original value is altered.


=== Noncompliant code example

[source,javascript]
----
var b = a.reverse(); // Noncompliant
var d = c.sort(); // Noncompliant
----


=== Compliant solution

[source,javascript]
----
var b = [...a].reverse();  // de-structure and create a new array, so reverse doesn't impact 'a'
a.reverse();

c.sort(); // this sorts array in place
----


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