What is the most effective way to eliminate asynchronicity in a function?

Imagine having this block of code:

const myFunction = async => {
  const result = await foobar()
}

const foobar = async () => {
  const result = {}
  result.foo = await foo()
  result.bar = await bar()
  return result
}

Now, let's transform it to:

const myFunction = () => {
  const result = foobar()
}

Attempted to modify foobar using the following:

const foobar = async () => {
  return (async () => {
    const result = {}
    result.foo = await foo()
    result.bar = await bar()
    return result
  })()
}

However, this approach still yields a promise

It is not possible to use .then in myFunction, as it is necessary for foobar to return the result variable instead of a promise.

The issue arises from myFunction being an async function, resulting in a promise return, while the desired outcome is to obtain undefine by eliminating async from myFunction.

Update: per Sebastian Speitel's suggestion, the intent is to convert myFunction to synchronous.

Update 2: addressing Shilly's comment, the context involves using nightwatch for end-to-end testing. If myFunction() encounters an error during execution, the virtual machines in nightwatch will continue running indefinitely instead of stopping. This behavior is attributed to the async nature of the invoked function.

Answer №1

If you want to convert an asynchronous function into a synchronous one, all you need to do is remove the async keyword and any await keywords within the function.

const myFunction = async () => {
    const result = await foobar();
    // ...
    return 'value';
};

// can be changed to

const myFunction = () => {
    const result = foobar();
    // ...
    return 'value';
};

Remember, there is one crucial rule to bear in mind.

  1. If the return value of a function relies on the resolved promise(s), you cannot convert an asynchronous function into a synchronous one.

This implies that functions which contain promises but do not rely on their values for the return can function well as synchronous. In other cases, the asynchronous nature must be retained.

For a practical example, consider the code below, where myFunction's return value is not dependent on the promise being resolved.

const myFunction = () => {
    const result = foobar();

    result.then(data => doSomethingElse(data))
          .catch(error => console.error(error));

    return 'some value not dependent on the promise result';
};

To delve deeper into promises, it is recommended to explore the promises guide and the async/await page.

Answer №2

Have you considered trying out the .executeAsync() method and using the promise to call the .done() callback? This approach allows you to wrap the foobar function and contain either the asynchronous or any .then() calls within that wrapper.

Although my knowledge of nightwatch is a bit rusty, you might want to experiment with something like this:

() => {
  client.executeAsync(( data, done ) => {
    const result = await foobar();
    done( result );
  });
};

Alternatively, you could try:

() => {
  client.executeAsync(( data, done ) => foobar().then( result => done( result )));
};

Answer №3

If a function is labeled with async, it will always result in a Promise being returned. Take for example:

const foobar = async () => {
  return 7;
}

In this case, calling foobar will provide a Promise of 7. This behavior remains consistent regardless of whether the calling function is also async, or whether await is used when calling it.

The root of your issue lies not solely with myFunction, but with the use of async in foobar, which enforces the return of a Promise.

Given this limitation, it is likely you won't achieve your desired outcome. Async-Await simply serves as convenience for handling promises. Your attempt to return a synchronous value from an asynchronous operation goes against the nature of JavaScript.

Answer №4

There seems to be a crucial misunderstanding about the difference between synchronous and asynchronous code in this context.

It's important to note that not all async functions can simply be converted into synchronous functions. While you could use a callback pattern instead of async/await, it may not be as beneficial for your specific situation.

My suggestion would be to stick with the await keyword, as in your initial code example, and keep your functions async. This approach shouldn't disrupt the logic of your code.

Answer №5

Take a look at this code snippet

    function hello(){
      return 'hello'
    }
    function world(){
      return 'world'
    }
    const helloworld = () => {
        return new Promise((resolve)=>{
          let result = {}
          result.hello = hello()
          result.world = world()
          return resolve(result)
        })
    }

    const myFunction = () => {
      const result = helloworld()
      let response = {}
      result.then(val=>{
        response = Object.assign({}, val);
        return response
      });
    }

    var output = myFunction()
    console.log(output)

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