Practice: Promises

Directions

Fork and clone this lab. Respond to questions in clear, concise sentences directly within this markdown file.

1. What will the following code snippet log? Why?

console.log('Line 1')
setTimeout(() => console.log('Line 2'), 1000)
console.log('Line 3')

2. What does the following code snippet log? Why?

function createPromise(seconds) {
  return new Promise((resolve) => {
    setTimeout(function() {
      resolve(`After ${seconds} second(s), this promise is resolved.`)
    }, seconds * 1000)
  })
}

console.log(createPromise(1000))

3. How do we use our createPromise function to log "After 1 second(s), this promise is resolved."

4. What does the following code snippet return? What does it log?

const ouPromise = new Promise((resolve) => {
  resolve(12);
})

ourPromise.then(value => value * 2);

5. What does the last line of code return? What does it log?
Note: Instead of using the Promise constructor to create a Promise that immediately resolves to 12, we can just use the Promise.resolve method.

const ourPromise = Promise.resolve(12);
ourPromise.then(value => value * 2).then(value => value + 10);

6. What does the following code snippet return? What does it log? How does this differ from the question above?

Promise.resolve(12).then(value => value * 2).then(value => console.log(value + 10))

7. What does the following code snippet return? What does it log? How does this differ from the question above?

Promise.resolve(12).then(value => value * 2).then(value => {
  console.log(value + 10);
  return value + 10;
  });

8. What does the following code snippet return? What does it log? How does this differ from the question above?

Promise.reject(12).then(value => value * 2).then(value => {
  console.log(value + 10);
  return value + 10;
  }).catch(reason => {
    const message = `${reason} is a bad number.`;
    console.error(message);
    return reason;
  });