TypeScript: remove index signature using mapped types

Question

Given an interface (from an existing .d.ts file that can\'t be changed):

interface Foo {
  [key: string]: any;
  bar(): void;
}

Is there a

Answer 1

There is not a really generic way for it, but if you know which properties you need, then you can use Pick:

interface Foo {
  [key: string]: any;
  bar(): void;
}

type FooWithOnlyBar = Pick;

const abc: FooWithOnlyBar = { bar: () => { } }

abc.notexisting = 5; // error