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

interface AccountSelectParams {
  ...
}
const params = { ... };

const tmpParams: { [key in keyof AccountSelectParams]: any } | undefined = {};
  for (const key of Object.keys(params)) {
    const customKey = (key as keyof typeof params);
    if (key in params && params[customKey] && !this.state[customKey]) {
      tmpParams[customKey] = params[customKey];
    }
  }

please commented if you get the idea of this concept