What Is the Promise API?

As mentioned earlier, the Promise API helps manage asynchronous operations when making network requests to the server. It is a JavaScript object that contains the future values of an async operation, either a resolved value or a reason if it was rejected. A promise has three states:

• Resolved: The action/operation has succeeded.
• Rejected: The action/operation is failed.
• Pending: The action/operation is pending; it's not fulfilled or rejected yet.

We have seen how to fetch data using the promise-based Fetch API in Chapter 14; Fetching Data by Making API Requests, let's review that again and see what values are getting returned.

Let's add the following code in the Chrome Console window:

fetch('https://jsonplaceholder.typicode.com/posts/1')
  .then(function(res) {
    return res.json();
  }).then(function(data) {
    console.log(data);
  ...