awaited.ts

lib.es5.d.ts

type Awaited<T> = T extends null | undefined ? T : // special case for `null | undefined` when not in `--strictNullChecks` mode
    T extends object & { then(onfulfilled: infer F, ...args: infer _): any; } ? // `await` only unwraps object types with a callable `then`. Non-object types are not unwrapped
        F extends ((value: infer V, ...args: infer _) => any) ? // if the argument to `then` is callable, extracts the first argument
            Awaited<V> : // recursively unwrap the value
        never : // the argument to `then` was not callable
    T; // non-object or non-thenable