What is the importance of fulfilling a promise in resolving a response?

Question

What is the importance of fulfilling a promise in resolving a response?

I have a promise structured as follows:

let promise = new Promise((resolve, reject) => {
  axios.post("https://httpbin.org/post", params, header)
    .then(response => {
      resolve(Object.assign({}, response.data));
      // resolve("aaaa");
      console.log(response);
    })
    .catch(error => reject(error))
});

What is the significance of resolving this promise with response data?

If I were to replace

resolve(Object.assign({}, response.data));

with resolve("aaaa");, what would be the outcome?

Any assistance or clarification on this matter would be greatly appreciated. Thank you.

javascript vue.js promise axios

Answer 1

Answer №1

It is important to note that axios.post() already returns a Promise, so there is no need to wrap it in another promise.

Instead, you can do the following:

let promise = axios.post("https://httpbin.org/post", params, header)
  .then(response => {
    console.log(response);
    return Object.assign({}, response.data);
  });

// Later on...
promise.then(data => {
  console.log('Request successful:', data);
}, err => {
  console.log('Request failed:', err);
});

Creating a new Promise object is only required when you are not chaining off an existing promise, as shown in this example:

function delay(duration) {
  return new Promise(resolve => setTimeout(resolve, duration));
}

delay(1000).then(() => {
  console.log('this code is delayed by 1s');
});

Answer 2

It is important to note that axios.post() already returns a Promise, so there is no need to wrap it in another promise.

Instead, you can do the following:

let promise = axios.post("https://httpbin.org/post", params, header)
  .then(response => {
    console.log(response);
    return Object.assign({}, response.data);
  });

// Later on...
promise.then(data => {
  console.log('Request successful:', data);
}, err => {
  console.log('Request failed:', err);
});

Creating a new Promise object is only required when you are not chaining off an existing promise, as shown in this example:

function delay(duration) {
  return new Promise(resolve => setTimeout(resolve, duration));
}

delay(1000).then(() => {
  console.log('this code is delayed by 1s');
});

Answer 3

Answer №2

resolve() is a function that lives up to its name by resolving the promise and returning the value specified within the function call.

For instance, if you have a promise that resolves with resolve('aaaaa'), it means that your promise will be successful and its value will be 'aaaaa'.

On the other hand, you can also choose to reject the promise, indicating that the operation failed at some point. Similar to resolve(), reject() takes a parameter that determines the value promised to be returned.

Answer 4

resolve() is a function that lives up to its name by resolving the promise and returning the value specified within the function call.

For instance, if you have a promise that resolves with resolve('aaaaa'), it means that your promise will be successful and its value will be 'aaaaa'.

On the other hand, you can also choose to reject the promise, indicating that the operation failed at some point. Similar to resolve(), reject() takes a parameter that determines the value promised to be returned.

Answer 5

Answer №3

The only action it will take is invoking the success callback resolve with the value "aaaa" instead of its original content.

For example, if you provide the function console.log as the callback, and the promise resolves successfully, then the callback will execute with the specified argument (console.log("aaaa"))

If the promise does not resolve - if it fails - then the reject callback will be triggered based on your defined .catch() statement.

Answer 6

The only action it will take is invoking the success callback resolve with the value "aaaa" instead of its original content.

For example, if you provide the function console.log as the callback, and the promise resolves successfully, then the callback will execute with the specified argument (console.log("aaaa"))

If the promise does not resolve - if it fails - then the reject callback will be triggered based on your defined .catch() statement.

Answer 7

Answer №4

When working with promises, you have two functions at your disposal: resolve and reject. These functions allow you to send a response back to the calling code. If your promise completes successfully, you use resolve() to send the desired response. However, if an error occurs, you can use reject(), typically passing the error as an argument.

The parameter passed to the resolve function will be received in the then callback, while the reject function's parameter can be accessed in the catch block.

For instance:

function myFunction(){
    return new Promise((resolve, reject) => {
        try{
            /* Perform asynchronous tasks here */
            resolve(result); // The result will be available in the "then" block
        } catch(e){
            reject(e);
        }
    });
}

myFunction().then((response) => {
    /* Handle the response here*/
}).catch((err) => {
    console.error(err);
}

Think of resolve as a way to return a value in an asynchronous setting, while reject is similar to throwing an exception that can be caught by the calling code.

Therefore, using resolve(myVariable) will pass myVariable back to the calling code, while resolve('aaa') will always return "aaa".

Answer 8

When working with promises, you have two functions at your disposal: resolve and reject. These functions allow you to send a response back to the calling code. If your promise completes successfully, you use resolve() to send the desired response. However, if an error occurs, you can use reject(), typically passing the error as an argument.

The parameter passed to the resolve function will be received in the then callback, while the reject function's parameter can be accessed in the catch block.

For instance:

function myFunction(){
    return new Promise((resolve, reject) => {
        try{
            /* Perform asynchronous tasks here */
            resolve(result); // The result will be available in the "then" block
        } catch(e){
            reject(e);
        }
    });
}

myFunction().then((response) => {
    /* Handle the response here*/
}).catch((err) => {
    console.error(err);
}

Think of resolve as a way to return a value in an asynchronous setting, while reject is similar to throwing an exception that can be caught by the calling code.

Therefore, using resolve(myVariable) will pass myVariable back to the calling code, while resolve('aaa') will always return "aaa".

What is the importance of fulfilling a promise in resolving a response?

Answer №1

Answer №2

Answer №3

Answer №4

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