Operator '==' cannot be applied to types x and y in Typescript 2

Question

TypeScript Version: 2.0.2.0

Code I know the code is a bit stupid, but I actually have these kind of tests in my code (m

Answer 1

Faced the same issue in a scenario as the following:

let a: string;

a === 'some-value1' && a === 'some-value2';  // <==

The second line produces the same error and maybe because Typescript is smart enough to know that a string type at a given moment cannot contain two (or more) different string literals.

The correct approach for the above expression would be to use OR in the expression:

a === 'some-value1' || a === 'some-value2';  // works fine :)