export function getHotOffers () { let offerPromise = getRequest ('/hot-offers') .then (offers => JSON.parse (offers)); return offerPromise; } Similarly, any code that calls this will be getting a promise and will have to use its .then method to get the final value. It cannot succeed or fail twice, neither can it switch from success to failure or vice versa. Promise.all() return undefined. Modified 3 years, 11 months ago. :P. Thanks in advance for your help! Your title asks why new Promise is returning undefined, when the fact is that it isn't. It is indeed returning a valid promise. A promise represents the eventual result of an asynchronous operation. The documentation mentions it. stopAll () { startmeetingApi.stop ().then ( (res) => { this.transcript = res.data.transcript; }); console.log (this.transcript . change var promise = to return . None of the above worked and in my case the problem was that I was adding a mock in a __mocks__ directory next to the file, but the import used a 'scoped module'. The second one can now pass to the third .then() and so on. The reason it is returning undefined is because get_message () is not returning anything. If you added, say, return 'finished'; to the end of get_message (), then your var a would end up having the value 'finished' instead of undefined. Your code proceeds . While a Promise object is "pending" (working), the result is undefined. Promise Object Properties. You'll have to change the way you code. That's very convenient in practice. If the new Promise resolves, then two will also resolve by taking the new Promise 's resolved value as its own. function fetchIDs {. Fails in IE 11 with error SCRIPT5009: 'Promise' is undefined. Mar 16, 2022 P Paulie Guest Mar 16, 2022 #1 Paulie Asks: Firebase Promise Returning Undefined Data Javascript I've followed several guides on how to correctly wait for the data from my ListFile () function. The JavaScript language Promises, async/await June 18, 2022 Error handling with promises Promise chains are great at error handling. You need to return a promise for the result: function test(p) { return Promise.all(ccxt.exchanges.map(api => { //Looping . Your estimation () function returns undefined instead of returning a promise, that is because you return the new string from the callback function. Finally, then() returns a new Promise that resolves to JSON. fmarsella February 15, 2021, 1:57pm #1. When a Promise object is "fulfilled", the result is a value. My recommendation is to restructure the code to use promises throughout. If you return a Promise, the resolution of this two determined by the fate of this new Promise. And we can not access the real output when it is available using the Promise return by the function. For that you need to use the original Promise constructor. Target is to fetch pets from api and if pet not exist to return altered array with only existing pet names. If it rejects, it is rejected with the reason from the first promise that was rejected. When a Promise object is "rejected", the result is an . doesn't return anything, the promise returned by then gets resolved with an undefined value. You will need to use the promise to get access to the offers. Return value A Promise that is resolved with the given value, or the promise passed as value, if the value was a promise object. If a function returns a Promise, it means that the result of the function call is not available. It does return a promise but does not have the ability to convert callback based functions to Promises that can be used with await. Why is Promise.all returning the array without waiting on the requests'results? From Node Lecture Asynchronous JavaScript : 8- Consuming Promises Hello Forum, I'm confused why the third then( ) always return undefined. Promise.resolve (value) catch (error) {.} to be compatible with ES5. This resulting Promise is received by the then() method, which parses the response to JSON using the json() method. If a promise has succeeded or failed and you later add a success/failure callback, the correct callback will be called, even though the event took place earlier. getId Cannot read property 'then' of undefined . Use of setTimeout () function. You cannot return data that is being loaded asynchronously. I had to add a folder for the scoped module under the root mocks folder ie __mocks__/@module/file.js. This returned promise fulfills when all of the input's promises fulfill (including when an empty iterable is passed), with an array of the fulfillment values. Click an available time slot on the calendar below to reserve a room. Promise.all(promises) .then(objects => { var music = objects[0] console.log("music", objects[0]) // This prints out "music undefined" profile.music = music } The weird thing is when I print out the iTunes api result that I'm returning in the promise, it prints fine. This makes the promise created by thenresolve with the value undefined. W3Guides. - Jaromanda X Jun 22, 2017 at 6:36 To do that there is two popular way described below. Try it Syntax Promise.all(iterable) Parameters iterable An iterable (such as an Array) of promises. I am resolving it and returning it to my title in my . Angular 5 Promise returns undefined, Angular service returning undefined to component, Angular 2 - Http with promise return Undefined, Angular observable return undefined results. Just return the promise directly. You get a promise of a result. The promise.then() call always returns a promise. When a promise rejects, the control jumps to the closest rejection handler. Promise resolver undefined is not a function at new Promise (<anonymous>) The fix is straightforward: you must provide a way to resolve or reject promises: // Instead of this const promise = new Promise() // do this const promise = new Promise(() => {}) That will fix the problem. Answer 1. It may be either fulfilled or rejected for example, resolving a rejected promise will still result in a rejected promise. In Example 2, the getGithubOrgs(url) function calls the Fetch API, which returns a Promise that resolves to a response object. When the first .then method returns a value, the next .then method can receive that. But how can I use .then () to get and use the response in the vue file. When a Promise is created, it will be pending. I know the query returns data when the function executes, it however does not seem to pass that data to the actual return part of the function call. I hope that was clear enough! Examples 1 People found this is helpful async-await javascript node.js Advertisement with return countQuery.then (.). If you try running the above code, the result logged will be undefined. Cleaner, simpler. A promise can only succeed or fail once. This means that you have to provide an onRejected function even if you want to fall back to an undefined result value - for example obj.catch(() => {}). I have logged the output to the console in ListFile () so I know the data is correct. The argument is a function providing two arguments: a resolve and . However, in the promise completion block it's always undefined. Home Web Design Programming Languages Database Design and Development Software Development Tools Artificial Intelligence Mobile Development Computer Science. So instead of: var list = _getById({ groupId: 42}); console.log("Our list is: "+list); You'll: Already have an account? If you want a promise of an optional that is fine, but your T should be T|undefined in this case. Blockquote To make the function promisedDivision (n1, n2) return a rejected promise let's set the second argument to 0. replace countQuery.then (.) For instance, in the code below the URL to fetch is wrong (no such site) and .catch handles the error: But whenever I use it, it always says that .then () is undefined. This means you will get undefined as the return value of apiGetAll. How to return data from promise; Export Cookie Jar to JSON with Node Request; node.js call external exe and wait for output; node.js resolve promise and return value; How can I send an object to a file, process that object, return and get the result because I'm missing something here and I do not understand why I get undefined and my Promise . As an async function, readThatSHIT wraps the empty return value (undefined) in a promise and returns that. remove the promise.then null function, and finally, realise that var result = fileExists ("url_to_file"); will mean result is a Promise - if you want to wait for the promise to fulfill you'll need to do result.then (function (result) { . This happens because after making a call to getResult method, it in turns calls the getPromise method which gets resolved only after 2000 ms. getResult method doesn't wait since it doesn't returns a promise. Your test function does return a undefined. archy-bold commented on Sep 6. to see whether the rejected promise is caught. Runs without error in IE11. Promise is replaced with callbacks, etc. If we are now returning anything inside two, TypeScript will replace the previous Hey with an undefined. There are a number of copies of this issue floating around and most of them are labeled as a dupe of #4260 , however on cursory glance of that issue I think perhaps the reality is that #4260 is a a prerequisite before fixing this issue. So const api will always equal undefined. Advanced Search Only show rooms with the following amenities: 65" J-Touch: HDMI Wired Connectivity Possible: Local PC It behaves the same as calling Promise.prototype.then(undefined, onRejected) (in fact, calling obj.catch(onRejected) internally calls obj.then(undefined, onRejected)). It allows us to call the next .then method on the new promise. Viewed 3k times -1 I have have array with three pet names. When calling a function that returns a promise, comes back as undefined unless async operators are removed, then returns ZoneAwarePromise, but contains no data. A promise can be one of the three states below. [Solved]-NodeJS - Promise returns undefined object inside a redis pool await-node.js score:0 Accepted answer in your attempts you use await configPool.get ('allImages', async (err, reply) => { firstly, .get doesn't return a promise, so await ing it makes no sense secondly, you're not using await inside the callback, so no need to make it async This promise will have the state as pending and result as undefined. Answers related to "return undefined on async method js" async function javascript promise async async function javascript dec javascript return data async javascript await return value javascript make async get request .then (async async await catch reject async function in variable Async return values Get async: false js undici fetch data async Promise is returning undefined. Share Follow answered Aug 18, 2015 at 6:49 Matt Way 31.4k 10 77 83 4 Thanks Matt - your suggested change makes it work as expected. A JavaScript Promise object can be: Pending; Fulfilled; Rejected; The Promise object supports two properties: state and result. You probably meant to have it return the new promise you're creating, but you're not doing that until the setTimeoutcallback. Use of async or await () function. // create an array of items from obj const items = Object.keys (obj); // turn it to an array of promises for database queries But async/await would have made it clearer that you have to set state in the the callback because the value doesn't exist until the promise returns. I think I know why, because I return the Axios within an async function. Problem is that Promise.all() return undefined. If the returned promise fulfills, it is fulfilled with the value of the first promise in the iterable that fulfilled. always return 'undefined' Node. It is just that resolve is not a valid function on the promise object. Promise then(.) You want to do it prior (but there's more, keep reading): let throttleAsync = function(url) { return promise.then(() => { angularjs; javascript; angular-promise; 2022-07-27 11:25. code to use result .}) you're currently immediately resolving your outer promise but with an inner promise, and that inner promise doesn't return anything at all, hence undefined. I know the query returns data when the function executes, it however does not seem to pass that data to the actual return part of the function call. throws an error, the promise returned by then gets rejected with the thrown error as its value. Stack Overflow - Where Developers Learn, Share, & Build Careers I'm trying to get a value back from this promise but it keeps returning undefined on my template.If you look at my getLabel function, I am getting the label in the argument which is a promise. JavaScript - Cannot read property 'then' of undefined. edited to join this conversation on GitHub . returns an already fulfilled promise, the promise returned by then gets fulfilled with that promise's value as its value. Promise.reject (reason) Returns a new Promise object that is rejected with the given reason. It rejects when any of the input's promises rejects, with this first rejection reason. Promise.resolve(r) fetchIDs (GET ). In some cases, you may want to check the status of the promise. Instead of "get the id, then do something with it", you need to "do something whenever the id is loaded/changed". Ask Question Asked 3 years, 11 months ago. When calling a function that returns a promise, comes back as undefined unless async operators are removed, then returns ZoneAwarePromise, but contains no data. Because promisedDivision (n1, 0) now would return rejected promises, let's also wrap the invocation into a try {. } If not let mw know! The catch() method returns a Promise and deals with rejected cases only. Description The static Promise.resolve function returns a Promise that is resolved. Use of setTimeout () function: In order to wait for a promise to finish before returning the variable, the function can be set with setTimeout (), so that the function waits for a few milliseconds. 8 People found this is helpful async-await javascript promise reactjs Advertisement One is incorrect. If you still want to use promises, that's fine. Only works in IE 11 if bluebird.min.js script element is uncommented. The primary way of interacting with a promise is through its then method, which registers callbacks to receive either a promise's eventual value or the reason why the promise cannot be fulfilled. Therefore, the correct way to get an array of promises is as follows: The first state is called the Pending state. 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