rspec/rules/S4140/javascript/rule.adoc

== Why is this an issue?

An array declared with missing ("sparse") elements is likely to be an error: an extra comma was inserted or perhaps the developer meant to insert the missing value and forgot.


=== Noncompliant code example

[source,javascript]
----
let a = [1, , 3, 6, 9];  // Noncompliant
----


=== Compliant solution

[source,javascript]
----
let a = [1, 3, 6, 9];
----


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

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

=== Message

Either supply the missing element or remove the extra comma


=== Highlighting

The sparse comma


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

=== on 8 Nov 2017, 09:56:07 Michael Gumowski wrote:
Removing PHP from the list of targeted language. You can not declare sparse arrays in PHP. The following code does not compile:

----
$array = [1, 2, 3, , 4];
----

However, sparse arrays can also be seen as a feature of the language. In the following code, the array is defined with 3 values, but the internal representation of the array is a map, which will use 3 keys: ``++14++``, ``++15++`` and ``++42++``.

----
$array[14] = "hello";
$array[15] = "world";
$array[42] = "yolo";
----

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