Typescript type casting when destructuring [duplicate]

If Typescript can not deduce the type of the result of groupBy you could try asserting it yourself.

function groupBy(o: any) {
    return o; // return any
}

let x = { a: 1, b: "1" }

// we know better than tsc and assert the type
let {a, b} = <{ a: number, b: string }>groupBy(x);