Promises in ES6

// ES6 Promises

Promises are a way of managing asynchronous operations in JavaScript. They provide a way to ensure code is executed in the order it should, and provide a way to handle errors that may occur.

A promise can be thought of as a placeholder for a result or value that will eventually be provided by some asynchronous operation. This can be used to ensure that certain code will only be executed after the promise has been fulfilled.

Promises can be created using the Promise constructor. The constructor takes a single argument, which is a callback function. This callback function takes two arguments, resolve and reject. 

The resolve function is called when the asynchronous operation completes successfully and it is passed the result of the operation. 

The reject function is called when the asynchronous operation fails and it is passed the error that occurred.

Promises can be chained together to ensure that certain code will not be executed until the result of the previous promise is available. 

//Example

let promise1 = new Promise((resolve, reject) => {
  setTimeout(() => {
    resolve("Result of promise1");
  }, 2000);
});

let promise2 = new Promise((resolve, reject) => {
  setTimeout(() => {
    resolve("Result of promise2");
  }, 3000);
});

// Chaining Promises

promise1
  .then((result) => {
    console.log(result);
    return promise2;
  })
  .then((result) => {
    console.log(result);
  });

Promises are an excellent way to manage the execution of code, especially when dealing with asynchronous operations. They provide a way to ensure that code will only be executed after the promise has been fulfilled, and provide a way to handle any errors that might occur. Promises are created using the Promise constructor, which takes a single argument in the form of a callback function. This callback function has two parameters, resolve and reject, which are used to ensure the promise is fulfilled when the asynchronous operation is successful or rejected when the asynchronous operation fails. Promises can also be chained together to ensure that certain code will only be executed when the result from a previous promise is available. This can be useful when dealing with multiple asynchronous operations that need to be executed in a certain order. For example, two promises could be chained together so that the second promise will only be executed after the first promise has been fulfilled.