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

   developer.mozilla.org › en-US › docs

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   Oct 7, 2024 · All these methods take an iterable of promises (thenables, to be exact) and return a new promise. They all support subclassing, which means they can be called on subclasses of Promise, and the result will be a promise of the subclass type.

2. stackoverflow.com › questions › 34094806javascript - Return from a promise then () - Stack Overflow

   stackoverflow.com › questions › 34094806

   Dec 28, 2019 · To use a promise, you have to either call a function that creates a promise or you have to create one yourself. You don't really describe what problem you're really trying to solve, but here's how you would create a promise yourself: function justTesting(input) {. return new Promise(function(resolve, reject) {.

3. developer.mozilla.org › en-US › docsUsing promises - JavaScript | MDN - MDN Web Docs

   developer.mozilla.org › en-US › docs

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   Oct 7, 2024 · doSomethingElse and doThirdThing can return any value — if they return promises, that promise is first waited until it settles, and the next callback receives the fulfillment value, not the promise itself.

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. masteringjs.io › tutorials › fundamentalsUnderstanding `new Promise` in JavaScript - Mastering JS

   masteringjs.io › tutorials › fundamentals

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   Jan 24, 2020 · You don't need to create new promises very often. Usually, libraries like Axios or Mongoose create promises internally and return them, so you can use then() or await. However, not all APIs support promises. For example, the setTimeout() function only accepts callbacks.

6. 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 · With a promise-based API, the asynchronous function starts the operation and returns a Promise object. You can then attach handlers to this promise object, and these handlers will be executed when the operation has succeeded or failed.

7. People also ask

   How to return a promise in JavaScript?

   • document.write(x); Or, if you already have a function that returns a promise, you can use that function and return its promise: return new Promise(function(resolve) { setTimeout(function() { resolve(); }, t); }); return delay(100).then(function() { return input + 10; }); // you access the value from the promise here log(val); document.write(x);

   javascript - Return from a promise then () - Stack Overflow

   stackoverflow.com/questions/34094806/return-from-a-promise-then

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   How do I create a promise in JavaScript?

   • To use a promise, you have to either call a function that creates a promise or you have to create one yourself. You don't really describe what problem you're really trying to solve, but here's how you would create a promise yourself: return new Promise(function(resolve, reject) { // some async operation here setTimeout(function() {

   javascript - Return from a promise then () - Stack Overflow

   stackoverflow.com/questions/34094806/return-from-a-promise-then

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   What is a new promise in JavaScript?

   • new Promise(executor); Your executor function is responsible for calling resolve() to mark the promise as fulfilled (successful) or rejected (failed). resolve('OK'); const fail = new Promise(function executor(resolve, reject) { reject(new Error('Oops')); const str = await success;

   Understanding `new Promise` in JavaScript - Mastering JS

   masteringjs.io/tutorials/fundamentals/promise-new

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   How do I return a new promise?

   • return new Promise(function(resolve, reject) { resolve('start of new Promise'); }); console.log('3rd then, after calling test: ' + value); For your questions: You return the Promise together with all the chained then functions. If you add another then to the returned Promise, it will be added at the end of the chain.

   javascript - Return promise from the function - Stack Overflow

   stackoverflow.com/questions/40735418/return-promise-from-the-function

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   Can a promise resolve a value?

   • The MDN text explains that you can either construct a new Promise that resolves, or just return any value (which will then be automatically wrapped in a Promise and resolved for you). Leaving the return statements out would also not allow you to pass along information from then to then.

   javascript - Return promise from the function - Stack Overflow

   stackoverflow.com/questions/40735418/return-promise-from-the-function

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   What is a JavaScript promise object?

   • 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. When a Promise object is "fulfilled", the result is a value.

   JavaScript Promises - W3Schools

   www.w3schools.com/Js/js_promise.asp

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8. 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.