Unable to index typescript object

Question

This is what I have:

export const ID1 = "id1";
export const ID2 = "id2";
export const ID3 = "id3";

export const MAPPING1 = "MAPPING1";
export const MAPPING2 = "MAPPING2";
export const MAPPING3 = "MAPPING3";

export const MAPPINGS = {
    ID1: MAPPING1,
    ID2: MAPPING2,
    ID3: MAPPING3
};

const finalMapping = MAPPINGS[key as keyof typeof MAPPINGS] || "NOTFOUND"

where key is a string. I've printed out test values like so:

console.log("key = " + key + " with type: " + (typeof key));
// prints this: key = ID1 with type: string

But finalMapping ends up always being NOTFOUND for me. Why am I unable to index the MAPPINGS object properly?

Answer 1

Not sure why this works, but it does:

export const MAPPINGS = {
    ID1: MAPPING1,
    ID2: MAPPING2,
    ID3: MAPPING3
};

to

export const MAPPINGS = {
    [ID1]: MAPPING1,
    [ID2]: MAPPING2,
    [ID3]: MAPPING3
};