Is some syntax exists for type annotation of decomposed to declared in advance variables array?

Question

In my standard, all types annotations where possible are required, so TypeScrit-ESLint tells me to annotate the [ responseData, cognitoUser ]. However, the syntax [ responseData1: ResponseData1, responseData2: ResponseData2] is invalid (TS1005: ';' expected). If there is no such syntax, it's the issue in TypeScript/ESLint repository.

let responseData1: ResponseData1;
let responseData2: ResponseData2;

try {
  [ responseData1, responseData2] = await Promise.all([ /* ... */ ])
} catch {
 // ...
}

Answer 1

From TS 4 you can add labels for array types.

type ResponseData = [responseData1: ResponseData1, responseData2: ResponseData2];

And you can use it for your Promise.all:

try {
  const [responseData1, responseData2]: ResponseData = await Promise.all([ /* ... */ ])
} catch {
 // ...
}

Answer 2

Here is a overall pattern you need to follow for destructuring from Promise.all and catch the errors:

function getFoo(): Promise<number> {
  return Promise.resolve(2);
}

function getBar(): Promise<number> {
  return Promise.resolve(3);
}

async function getResults(): Promise<{ foo: number; bar: number }> {
  try {
    const [foo, bar] = await Promise.all([getFoo(), getBar()]);
    return { foo, bar };
  } catch (e) {
    throw new Error("something went wrong.");
  }
}