Enforcing the type of the indexed members of a Typescript object?

Question

I would like to store a mapping of string -> string in a Typescript object, and enforce that all of the keys map to strings. For example:

var stuff = {};
st         


        

Answer 1

var stuff: { [key: string]: string; } = {};
stuff['a'] = ''; // ok
stuff['a'] = 4;  // error

// ... or, if you're using this a lot and don't want to type so much ...
interface StringMap { [key: string]: string; }
var stuff2: StringMap = { };
// same as above