Type definition in object literal in TypeScript

Question

In TypeScript classes it\'s possible to declare types for properties, for example:

class className {
  property: string;
};

How do declare

Answer 1

If your properties have the same type, you could use predefined utility type Record :

type Keys = "property" | "property2"

const obj: Record = {
  property: "my first prop",
  property2: "my second prop",
};

You can of course go further and define a custom type for your property values:

type Keys = "property" | "property2"
type Values = "my prop" | "my other allowed prop"

const obj: Record = {
  property: "my prop",
  property2: "my second prop", // TS Error: Type '"my second prop"' is not assignable to type 'Values'.
};