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1. • • In JavaScript, a promise is a placeholder (proxy) for the value of an ongoing operation. You typically use a promise to manage situations where you must wait for the outcome of an operation. For example, uploading files to the server and awaiting the response of an API call, or just asking the user to choose a file from their computer.
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     JavaScript Promises for Beginners - freeCodeCamp.org

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   What is a promise in JavaScript?

   • A Promise contains both the producing code and calls to the consuming code: When the producing code obtains the result, it should call one of the two callbacks: A JavaScript Promise object can be: The Promise object supports two properties: state and result. While a Promise object is "pending" (working), the result is undefined.

   JavaScript Promises - W3Schools

   www.w3schools.com/Js/js_promise.asp

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   What is a promise object?

   • The Promise object represents the eventual completion (or failure) of an asynchronous operation and its resulting value. To learn about the way promises work and how you can use them, we advise you to read Using promises first. A Promise is a proxy for a value not necessarily known when the promise is created.

   Promise - JavaScript | MDN - MDN Web Docs

   developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise

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   How to resolve a promise in JavaScript?

   • Promise.any() accepts an array of Promises as an argument but returns a single Promise as the output. The single promise it returns is the first resolved promise in the input array. This method waits for any promise in the array to be resolved and would immediately return it as the output.

   How Promises Work in JavaScript – A Comprehensive Beginner's Guide

   www.freecodecamp.org/news/guide-to-javascript-promises/

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   What is a single Promise in JavaScript?

   • The single promise it returns is the first resolved promise in the input array. This method waits for any promise in the array to be resolved and would immediately return it as the output. From the above example, promise1 will resolve after 3 seconds, promise2 will resolve after 2 seconds, and promise3 immediately rejects.

   How Promises Work in JavaScript – A Comprehensive Beginner's Guide

   www.freecodecamp.org/news/guide-to-javascript-promises/

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   How do I create a promise using a new keyword?

   • You can create a Promise using the new keyword with the Promise constructor. The Promise constructor takes a callback function that takes two arguments, called resolve and reject. Each of these arguments is a function provided by the Promise, which are used to transition the Promise to either the fulfilled or rejected state.

   How JavaScript Promises Work – Handbook for Beginners

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   How to create a callback for a promise in JavaScript?

   • To create a callback for a promise, you need to use the .then() method. This method takes in two callback functions. The first function runs if the promise is resolved, while the second function runs if the promise is rejected. console.log(value); } function handleReject(reason) { console.error(reason); }

   How Promises Work in JavaScript – A Comprehensive Beginner's Guide

   www.freecodecamp.org/news/guide-to-javascript-promises/

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3. developer.mozilla.org › Guide › Using_promisesUsing promises - JavaScript | MDN - MDN Web Docs

   developer.mozilla.org › Guide › Using_promises

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   Oct 7, 2024 · A Promise is an object representing the eventual completion or failure of an asynchronous operation. Since most people are consumers of already-created promises, this guide will explain consumption of returned promises before explaining how to create them.

4. www.w3schools.com › Js › js_promiseJavaScript Promises - W3Schools

   www.w3schools.com › Js › js_promise

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   Here is how to use a Promise: myPromise.then(. function(value) { /* code if successful */ }, function(error) { /* code if some error */ } ); Promise.then () takes two arguments, a callback for success and another for failure. Both are optional, so you can add a callback for success or failure only.

5. www.freecodecamp.org › news › the-javascriptHow JavaScript Promises Work – Handbook for Beginners

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   Feb 13, 2024 · Table of Contents. What is a Promise? Comparing Promises to Other Async Patterns. How to Create a Promise. How to Get the Result of a Promise. How to Handle Errors with then. Promise Chaining. How to Create Immediately Fulfilled or Rejected Promises. How to Use async and await. Promise Anti-Patterns. Summary. What is a Promise?

6. www.freecodecamp.org › news › guide-to-javascriptHow Promises Work in JavaScript – A Comprehensive Beginner's ...

   www.freecodecamp.org › news › guide-to-javascript

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   Jun 13, 2023 · Here are the topics we will cover: Why should you care about promises? What is a promise? How to create a promise in JavaScript. How to attach a callback to a promise. How to handle errors in a promise. How to handle many promises at once. What is the async/await syntax? How to create an async function in JavaScript. How to use the await keyword.

7. www.aleksandrhovhannisyan.com › blog › javascriptJavaScript Promises: Practical Use Cases and Examples

   www.aleksandrhovhannisyan.com › blog › javascript

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   Sep 12, 2020 · With ES2015, JavaScript finally introduced the Promise: an object that may or may not contain some value at some point in the future. Promises offer a powerful and legible syntax for writing asynchronous code in JavaScript. This post assumes a basic understanding of Promises and how they work.

8. developer.mozilla.org › en-US › docsPromise - JavaScript | MDN - MDN Web Docs

   developer.mozilla.org › en-US › docs

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   Oct 7, 2024 · To learn about the way promises work and how you can use them, we advise you to read Using promises first. Description A Promise is a proxy for a value not necessarily known when the promise is created.

9. developer.mozilla.org › Asynchronous › PromisesHow to use promises - Learn web development | MDN - MDN Web Docs

   developer.mozilla.org › Asynchronous › Promises

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   Jul 25, 2024 · The async and await keywords make it easier to build an operation from a series of consecutive asynchronous function calls, avoiding the need to create explicit promise chains, and allowing you to write code that looks just like synchronous code.