Typescript: bracket notation property access

I added it as a separate interface because i need to keep original..

export interface IIndexable {
  [key: string]: any;
}

and referencing it when needed

getEditDate(r: IRestriction, fieldName: string) {
    ...
    value={(r as IIndexable)[fieldName] as Date}

works well. i will update if i find a way to shorten it

Instead of using a variable in obj[x], you can write:

obj["bar"].sort

The only reason to use a variable here is to choose an arbitrary property from your IFoo interface. You seem to only have one. If you had many string arrays on your IFoo, you could make it indexable and write:

interface IFoo {
    bar: string[];
    bar2: string[];
    [key: string]: string[]; // IFoo is indexable; not a new property
}

Which would allow you to write:

var name = "bar";
obj[name].sort;

But it would also allow you to write:

obj["some new property"] = ["a", "b"];
obj["some new property"].sort;