Typescript Types

Mapped Types

In TypeScript, you can define an object type where the keys are strings and the values are also strings using an index signature:

interface StringObject {
  [key: string]: string;
}

const myObject: StringObject = {
  name: "Mariappan",
  city: "Tamilnadu"
};

Explanation:

• [key: string]: string;: This is an index signature. It defines that any key within the object must be a string, and the corresponding value associated with that key must also be a string.
• StringObject: This is an interface that acts as a blueprint for the object you want to create.
• myObject: This is an object that conforms to the StringObject interface.

Wiki

1. Exploring [key:string]: any in TypeScript
2. Mapped Types - official
3. Index Signatures
4. Enforcing the type of the indexed members of a Typescript object? - stackoverflow
5. TypeScript Function Types: A Beginner's Guide