Why Does My Asynchronous Function Return `Promise { }` Instead of a Value?

Asynchronous Function Returning Promise { } Instead of a Value

As demonstrated in the provided code, asynchronous functions often return a Promise, which represents the eventually available value. However, when attempting to access its value immediately, the console logs "Promise { }" due to the unresolved state of the Promise.

Resolving Promise Values

To obtain the desired token value, you must chain a ".then" handler to your promise. This handler captures the resolved result, whether it's already available or still pending:

let AuthUser = (data) => {
  return google.login(data.username, data.password).then((token) => {
    return token;
  });
};

let userToken = AuthUser(data);
userToken.then((result) => {
  console.log(result); // "Some User Token"
});

Promise Resolution Details

Promises adhere to the Promises/A specification, which mandates a specific resolution procedure:

• If the ".then" handler returns a value, the Promise resolves to that value.
• If the handler returns another Promise, the Promise resolves to the resolved value of the chained Promise.

Understanding Promise Chaining

Each ".then" handler's resolved value becomes the next handler's input, enabling a chain of asynchronous operations. The following examples illustrate this behavior:

Value Return:

function initPromise() {
  return new Promise((res, rej) => {
    res("initResolve");
  });
}

initPromise()
  .then((result) => {
    console.log(result); // "initResolve"
    return "normalReturn";
  })
  .then((result) => {
    console.log(result); // "normalReturn"
  });

Chained Promise Return:

function initPromise() {
  return new Promise((res, rej) => {
    res("initResolve");
  });
}

initPromise()
  .then((result) => {
    console.log(result); // "initResolve"
    return new Promise((resolve, reject) => {
      setTimeout(() => {
        resolve("secondPromise");
      }, 1000);
    });
  })
  .then((result) => {
    console.log(result); // "secondPromise"
  });

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