Optimizing Network Requests with Promises

The Problem: Sequential Requests

Traditionally, making multiple network requests in JavaScript would require you to chain them sequentially. This can be inefficient, as each request blocks until the previous one completes. This is particularly noticeable with the I/O bound nature of HTTP requests.

                
                    // Inefficient approach
                    fetch('url1')
                        .then(response => response.json())
                        .then(data1 => {
                            // Process data1
                            fetch('url2')
                                .then(response => response.json())
                                .then(data2 => {
                                    // Process data2
                                    console.log('Data 1 and 2 processed');
                                });
                        });
                
            

Promises to the Rescue

Promises provide a cleaner and more efficient way to handle asynchronous operations, including network requests. They allow you to chain requests without blocking, and handle errors gracefully.

                
                    // Efficient approach using Promise.all
                    Promise.all([
                        fetch('url1').then(response => response.json()),
                        fetch('url2').then(response => response.json())
                    ])
                    .then(([data1, data2]) => {
                        // Process both data1 and data2
                        console.log('Data 1 and 2 processed');
                    })
                    .catch(error => {
                        console.error('Error:', error);
                    });
                
            

Explanation

Here's a breakdown of the code:

• Promise.all([promise1, promise2, ...]): Takes an array of promises and returns a new promise that resolves when all of the promises in the array have resolved.
• If any of the promises in the array reject, the new promise will also reject with the reason for the rejection.
• The resolved value of the new promise is an array containing the resolved values of the individual promises, in the same order as they were passed to Promise.all.