The TypeScript compiler automatically casts a variable to the relevant type inside conditionals where it is possible to infer the type (because ``++typeof++``, ``++instanceof++``, etc was used). This compiler feature makes casts and not-``++null++`` assertions unnecessary.


== Noncompliant Code Example

----
function getName(x?: string | UserName) {
  if (x) {
    console.log("Getting name for " + x!); // Noncompliant

    if (typeof x === "string")
      return (x as string); // Noncompliant
    else
      return (x as UserName).name; // Noncompliant
  }
  return "NoName";
}
----


== Compliant Solution

----
function getName(x?: string | UserName) {
  if (x) {
    console.log("Getting name for " + x);

    if (typeof x === "string")
      return x;
    else
      return x.name;
  }
  return "NoName";
}
----


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[]