Value of string literal type as property name.

[vilicvane]

For example:

type Method = 'get' | 'post';

let app = {
    get() { },
    post() { },
    foo() { },
    bar: 123
};

let methodA = 'get';
let handlerA = app[methodA]; // typeof handlerA === () => void

let methodB: Method;
let handlerB = app[methodB]; // typeof handlerB === () => void

[saschanaz]

See also #394 (or #1295?)

[vilicvane]

@saschanaz Thanks for the reference. So basically now we may have memberof operator return a string literal type, that's interesting. Hopefully somebody would take that PR.

[DanielRosenwasser]

I know @weswigham has brought this up, though I'm not sure if there's an existing issue for it.

[masaeedu]

@vilic What does the snippet demonstrate?

[vilicvane]

@masaeedu Hmm, I think it's about finding a common type among several properties (within the range of string literals union).

[mhegazy]

This should be addressed by the new indexing support for literal types in #11929