typeof x === "y" type guard not working in strict mode

[iscekic]

TypeScript Version: 2.4.0

Code

interface Repro {
  env: {
    [key: string]: string | undefined;
  };
}

const process: Repro = {
  env: {
    PORT: "3000"
  }
};

if (typeof process.env.PORT === "string") {
  parseInt(process.env.PORT);
}

Expected behavior:
The code is valid and passes compilation.

Actual behavior:
error TS2345: Argument of type 'string | undefined' is not assignable to parameter of type 'string'.
Type 'undefined' is not assignable to type 'string'.

[RyanCavanaugh]

Duplicate #10442 - we don't currently narrow except by declared properties, and there is no declared property named PORT

[Lord-Haji]

;D

…

On 05-Jul-2017 9:02 PM, "Ryan Cavanaugh" ***@***.***> wrote: Closed #16949 <#16949>. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#16949 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ARJAd937ZQkjTOKUc0FgnL500qWNSL0Rks5sK6yEgaJpZM4OOdtQ> .