How do you rename keys in a mapped type? type Getters = { [K in keyof T as `get${Capitalize }`]: () => T[K]; };

With as after in, using a template literal

It's impossible - keys in a mapped type always stay the same

With a rename() function from the standard type library

TypeScript · Middle · Question 28 of 75

How do you rename keys in a mapped type?

type Getters<T> = {
  [K in keyof T as `get${Capitalize<string & K>}`]: () => T[K];
};

✓Correct answer: With as after in, using a template literal
2It's impossible - keys in a mapped type always stay the same
3With a rename() function from the standard type library

Explanation

Key remapping (TS 4.1+): Getters<{ name: string }> → { getName: () => string }. If the expression after as produces never, the key is dropped - that's how properties are filtered by value type. string & K is needed because keys can be symbols or numbers.

How do you rename keys in a mapped type?

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