Promises in JavaScript - #30 @Everyday-Be-Coding

Promises in JavaScript are objects that represent the eventual completion (or failure) of an asynchronous operation, and its resulting value. Promises provide a cleaner and more structured way to handle asynchronous code compared to traditional callback-based approaches. Promises can be in one of three states:

Pending: The initial state of a promise. It represents that the asynchronous operation is still ongoing and hasn't resolved yet.

Fulfilled (Resolved): The state where the asynchronous operation has completed successfully, and the promise has a value.

Rejected: The state where the asynchronous operation has failed, and the promise has a reason for the failure.

Here's how you can create and use promises in JavaScript:

Creating a Promise:
You create a promise by using the Promise constructor, which takes a function (commonly referred to as the "executor") as an argument. The executor function receives two arguments: resolve and reject. You call resolve with the value when the asynchronous operation is successful, and reject with an error when it fails.

JavaScript code
const myPromise = new Promise((resolve, reject) =greater than {
// Asynchronous operation (e.g., fetching data, reading file)
setTimeout(() =greater than {
const data = "Hello, world!";
resolve(data); // Operation succeeded
// or
// reject(new Error("Failed to fetch data")); // Operation failed
}, 1000);
});
Consuming a Promise:
You consume a promise using the then() method to handle a successful resolution and the catch() method to handle a rejection.

JavaScript code:
myPromise
.then((result) =greater than {
})
.catch((error) = greater than {
});
Chaining Promises:
You can chain promises together using then() to execute multiple asynchronous operations sequentially.

JavaScript code:
fetchData()
.then((data) =greater than processData(data))
.then((processedData) =greater than displayData(processedData))
Async/Await:
ES8 introduced async and await keywords, which provide a cleaner syntax for working with promises. async marks a function as asynchronous, while await pauses the execution of an async function until a promise is resolved.

JavaScript code
async function fetchData() {
return new Promise((resolve, reject) =greater than {
setTimeout(() =greater than {
resolve("Hello, world!");
}, 1000);
});
}

async function process() {
try {
const data = await fetchData();
} catch (error) {
}
}

process();
Promises in JavaScript provide a powerful tool for managing asynchronous code and improving code readability, especially when dealing with complex asynchronous operations.

JavaScript Promises
ES6 Promises
JavaScript Asynchronous Programming
JavaScript Promise Tutorial
ECMAScript 2015 Promises
JavaScript Async/Await
Frontend Development
Web Development
JavaScript Tips and Tricks
Modern JavaScript

Chapter :
00:00 Promises in JavaScript
00:33 Callbacks
00:53 Creating Promises
01:16 Consuming a Promises
01:32 Chaining Promises
01:42 Async/Await
01:55 Summery

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