Argument of type 'string' is not assignable to parameter of type '"one" | "two" | "three" | "four" | "five" | "six"'

I have a type:

type OtpCode = {
  one: string;
  two: string;
  three: string;
  four: string;
  five: string;
  six: string;
};

and try to loop this object and set value :

Object.keys(defaultValues).forEach((x, i) => {
      codeValuesForm.setValue(x, 'sometesttext');
    });

x Type is OtpCode, and Typescript tells me that

Argument of type 'string' is not assignable to parameter of type '"one" | "two" | "three" | "four" | "five" | "six"'.

How can I solve this to loop this object?

>Solution :

Object.keys() sadly returns string[] and not a union of the keys on the object you pass in. There are many other answers on this which may help you find an appropriate solution, e.g.

• Why doesn't Object.keys return a keyof type in TypeScript?

• TypeScript: Object.keys return string[].

Most of the time you can get away with just manually type-casting, e.g.

Object.keys(defaultValues).forEach((key) => { key }); // string
(Object.keys(defaultValues) as (keyof OtpCode)[]).forEach((key) => { key }); // keyof OtpCode

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