Is it possible to constrain the values of an array with Typescript to a given subset of string values?

Question

Consider:

enum allowedValues {'x','y'}

export interface X {
  evaluation: string[]; // TODO: how to constrain to contain only the values 'x' or 'y';
}

I tried declaring evaluation as the enum: evaluation: shownEvaluation[]; I also tried evaluation: keyof allowedValues;

casieber · Accepted Answer · 2018-05-23 21:08:14Z

1

Yes! You need to declare a union type for the keys:

type allowedValues = 'x' | 'y';

export interface X {
    evaluation: allowedValues[];
}

answered May 23, 2018 at 21:08

casieber

7,6122 gold badges23 silver badges35 bronze badges

Sign up to request clarification or add additional context in comments.

1 Answer 1