TypeScript Convert Readonly

Have you ever wished you could convert all your mutable properties in a TypeScript object to readonly? Look no further! TypeScript provides a built-in utility type called Readonly that can convert mutable properties to readonly.

The Readonly Utility Type

The Readonly utility type takes an input type and returns a new type with all properties set to readonly. Here's an example of how to use Readonly to convert an interface with mutable properties to an interface with readonly properties:

interface MutablePerson {
  name: string;
  age: number;
}

type ReadonlyPerson = Readonly<MutablePerson>;

The ReadonlyPerson type now has readonly properties.

Converting Object Properties to Readonly

To convert an object's properties to readonly, you can use the as const assertion.

For example:

const person = {
  name: 'John',
  age: 30,
};

const readonlyPerson = {
  ...person,
} as const;

The as const assertion will convert all properties in readonlyPerson to readonly.

Conclusion

Converting mutable properties to readonly can help prevent bugs and make your code more robust. TypeScript provides a built-in utility type called Readonly that can convert mutable properties to readonly. You can also use the as const assertion to convert an object's properties to readonly.