Promise

1. What is Promise?

We can use callback function for using asynchronous processing. If so, the callback function can't iterate through various logic, low readability, Also, it is hard to handle exceptions errors. To solve these shortcomings, ES6 provide Promise

2. Callback Weakness

Callback Hell

Error Processing Limit

3. How to Create Promise

Promise State

State	Meaning	Materialization
Pending
Fulfilled
Rejected
Settled

How to Use Promise

Promise Chaining

Error handling in Promise

Static Method of Promise

Promise.resolve/Promise.reject

Promise.all

Promise.race