Typescript interface with named property and arbitrarily-named index properties of different type [duplicate]

Answer 1

Without defining every property, that's expected, but you can do this:

interface Foo1 {
    size: number;
    [name: string]: string|number;
}

Better than using any.

Answer 2

You can do something like this (I don't know if it will work in TS v1.5):

interface Size {
    size: number;
}

interface StringMap {
    [name: string]: string;
}

type Foo = Size & StringMap;