How can I map a list to a list of JSON?

I try to cast a list of strings [x, y, z] to
a list of JSON-objects [{str:x},{str:y},{str:z}].

Thats my try, but I get an error.

let lst:string [] = ["a", "b", "c"];

let foo:any [] = lst.map (l => {"str": l});

Error

error TS1005: ';' expected.
  let foo:any [] = lst.map (l => {"str": l});
                                       ~

>Solution :

While returing you need to use brackets(). Because we are inside a loop {} will be treated as block. So the updated code will be,

let lst: string[] = ["a", "b", "c"];

let foo: any[] = lst.map(l => ({ "str": l }));

Note ({"str": l})