解决承诺<pending>

Question

I'm looking to create a simple helper function which returns the hash for a given password using bcrypt but everytime i call the function, it resolves to Promises { <pending> } what am i doing wrong?

const saltPassword = async (password) => {
    const newHash = await bcrypt.hash(password, saltRounds, (err, hash) => {
        if (err) return err;
        return hash;
    });
    return await newHash;
}

cheers

Answer 1

You should do something like this

const saltPassword = async (password) => {
  const newHash = await bcrypt.hash(password, saltRounds, (err, hash) => {
    if (err) return err;
    return hash;
  });
  return newHash; // no need to await here
}

// Usage
const pwd = await saltPassword;

Answer 2

You need to return a Promise in order to use await . Simply wrap the callback function and call reject if there is an error or resolve if it was successful.

const saltPasswordAsync = (password, rounds) =>
    new Promise((resolve, reject) => {
      bcrypt.hash(password, rounds, (err, hash) => {
        if (err) reject(err);
        else resolve(hash)
      });
    });


async function doStuff() {
  try {
    const hash = await saltPasswordAsync('bacon', 8);
    console.log('The hash is ', hash);
  } catch (err) {
    console.error('There was an error ', err);
  }
}

doStuff();

Now you can use await to wait on the promise to resolve and use the value. To catch an error, wrap with a try/catch statement.

UPDATE

Thomas pointed out that you may not need to wrap the callback in a promise, since bcrypt returns a promise if you do not pass a callback function. You could replace the call to saltPasswordAsync above with bycript.hash like so:

const hash = await bcrypt.hash('bacon', 8);
console.log('The hash is ', hash);