Summary - Promises

JavaScript course · Intermediate · Lesson 77/134

Write a user-fetch-and-display flow using a promise chain.

Summary - Promises

In this group you learned the three promise states (pending, fulfilled, rejected), creating promises with new Promise, and chaining with then, catch and finally. You also saw Promise.all for parallel work.

Now you will put it all together in a flow: fetch and show a user's info using a promise chain.

Exercise User flow chain

A function called fetchUser returns a promise. Build this chain: call fetchUser; in then log the user's name property with console.log; in catch log the error with console.log; in finally call hideSpinner.

Show example solution

fetchUser()
  .then(user => console.log(user.name))
  .catch(error => console.log(error))
  .finally(() => hideSpinner());

Test yourself

Match the chain methods

then

Catches success
catch

Catches error
finally

Does cleanup
Promise.all

Waits in parallel

Complete the full chain

fetchUser()
  .then(user => console.log(user))
  .____(error => console.log(error))
  .finally(() => hideSpinner());

Show answer

fetchUser()
  .then(user => console.log(user))
  .catch(error => console.log(error))
  .finally(() => hideSpinner());

All lessons in Intermediate

1 Arrow functions

2 Scope

3 Closures

Summary - Promises