== Why is this an issue?

include::../description.adoc[]

{intro}

This rule detects repeatedly adding an element at the same index or key in a collection or adding identical elements to a set.

[source,javascript]
----
 fruits[1] = "banana";
 fruits[1] = "apple";  // Noncompliant

 myMap.set("key", 1);
 myMap.set("key", 2); // Noncompliant

 mySet.add(1);
 mySet.add(1); // Noncompliant
----

{outro}

ifdef::env-github,rspecator-view[]

'''
== Implementation Specification
(visible only on this page)

include::../message.adoc[]

include::../highlighting.adoc[]

'''
== Comments And Links
(visible only on this page)

include::../comments-and-links.adoc[]
endif::env-github,rspecator-view[]
