rspec/rules/S3402/javascript/rule.adoc

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 ``+`` or ``+=`` 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);
}
----


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'''
== Implementation Specification
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include::message.adoc[]

include::highlighting.adoc[]

'''
== Comments And Links
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include::comments-and-links.adoc[]
endif::env-github,rspecator-view[]