rspec/rules/S4622/javascript/rule.adoc

Union types represent a value that can be one of the several types. When a union type is used for a function parameter and it is accepting too many types, it may indicate the function is having too many responsibilities. Sometimes it's worth creating a type alias for this union type. In all cases, the code should be reviewed and refactored to make it more maintainable.


== Noncompliant Code Example

With the default threshold of 3:

[source,javascript]
----
let x: MyType1 | MyType2 | MyType3 | MyType4; // Noncompliant

function foo(p1: string, p2: MyType1 | MyType2 | MyType3 | MyType4) { // Noncompliant
    // ...
}
----


== Compliant Solution

[source,javascript]
----
type MyUnionType = MyType1 | MyType2 | MyType3 | MyType4; // Compliant, "type" statements are ignored
let x: MyUnionType; 

function foo(value: string, padding: MyUnionType) {
    // ...
}
----


== Exceptions

This rule ignores union types part of ``++type++`` statement:

----
type MyUnionType = MyType1 | MyType2 | MyType3 | MyType4;
----

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

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

include::message.adoc[]

include::parameters.adoc[]

include::highlighting.adoc[]

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