check following interface typescript code example

Example 1: typescript interface

interface Foo {
    bar: string;
    qux: number;
}
// Creates object implementing interface:
const MyFoo = <Foo> {
    bar: "Hello",
    qux: 7
}
// Or:
const MyFoo: Foo = {
    bar: "Hello",
    qux: 7
}

Example 2: typescript interface

interface NumberOrStringDictionary {
  [index: string]: number | string;
  length: number; // ok, length is a number
  name: string; // ok, name is a string
}Try