rspec/rules/S3402/javascript/rule.adoc

== Why is this an issue?

Use a ``+`` with two numbers and you'll get addition. But use it with a string and anything else, and you'll get concatenation. This could be confusing, especially if it's not obvious that one of the operands is a string. It is recommended to explicitly convert the non-string component to make it easier to understand to future maintainers.


This rule raises an issue when `pass:[+]` or `pass:[+=]` is used with a string and a non-string.


=== Noncompliant code example

[source,javascript]
----
function foo() {
  let x = 5 + 8;  // okay
  let z = "8"
  return x + z;  // Noncompliant; yields string "138"
}
----


=== Compliant solution

[source,javascript]
----
function foo() {
  let x = 5 + 8;
  let z = "8"
  return x + Number(z);
}
----


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

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

=== Message

Review this expression to be sure that the concatenation was intended.


=== Highlighting

* Primary: operator ``+``
* Additional: operands


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

=== on 20 Nov 2015, 17:20:49 Elena Vilchik wrote:
\[~ann.campbell.2] Perfect, thanks!

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