JavaScript Promise

1. What are the pros and cons of promises over callbacks

Pros:

• It avoids callback hell which is unreadable
• Easy to write sequential asynchronous code with .then()
• Easy to write parallel asynchronous code with Promise.all()
• Solves some of the common problems of callbacks(call the callback too late, too early, many times and swallow errors/exceptions)

Cons:

• It makes little complex code
• You need to load a polyfill if ES6 is not supported