Questions tagged [promise]

"Promises" are a particular tactic for deferred computing, suitable for several styles of concurrency: thread and event loop concurrency for local computation, and both synchronous and asynchronous remote messaging.

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Handling pure in browser HTTP request in Service Worker fetch event

I was suggested by @Bergi on StackOverflow that Async Promise constructors are any pattern. The argument behind this is that async Promise swallows the errors. In my case, I have try..catch so I'm not ...
0 votes
0 answers
341 views

Promise queue Typescript

As an exercise, I wrote a promise queue in Typescript. The point of it is to parallelise a maximum number of promises, and not just Promise.all() to batter the ...
3 votes
2 answers
108 views

Idempotent JavaScript script loader

I wrote an idempotent script loader (for the browser), where the same script won't be loaded more than once. scriptLoader.js: ...
2 votes
2 answers
865 views

Cleaning up nested promises in Cloud function

I am writing the Cloud function for Parse whose purpose is to update my database with a provided array of data objects. The main problem are the nested promises, which doesn't look right. Any help ...
1 vote
0 answers
206 views

Promise in an Express app to send OTP verification e-mail

In this code I'm using nodemailer for sending otp email from my gmail account. I have also used ejs for creating html templates for emails. This code works perfectly, but I am a bit concerned about ...
10 votes
1 answer
275 views

Nested cross-origin iframes for secure user-configurable javascript tools

Context I'm trying to build a system in which a tool (the Client) will generate a header to be used as part of an HTTP request from the user's browser. The user should be able to choose their own ...
0 votes
0 answers
247 views

Promise to save an image to Firebase and obtain the resulting URL

I'm trying to write a promise that will return me the image URL value that I'm getting from firebase once It is saved to the firebase storage. After some time I wrote the following code and it is ...
2 votes
1 answer
100 views

Basic node login routes for authentication system

I am building a basic authentication system with a node backend and wonder whether I am using the try-catch block excessively. I have this example controller: ...
2 votes
1 answer
138 views

Vue.js application, which fetches and displays list of seminars

I have a working application, which fetches list of events (seminars) from rest API. Functionality is quite simple: display list of seminars with possibility to filter upcoming/occured/all. The ...
14 votes
2 answers
39k views

Using async / await with dynamic import() for ES6 modules

I am experimenting with the best way to standardise my dynamic import() expressions when importing javascript modules. import() ...
2 votes
0 answers
265 views

JavaScript proxy for better stack traces from external libraries

I've been using the excellent pg-promise library for a few years now, but my primary irk with it is that the stack traces are sometimes unhelpful. For example, the following test will fail (currently ...
1 vote
1 answer
386 views

React Native login, sign up and sign out using Firebase project

I have built a basic app which uses firebase for authentication. The app is pretty simple. Sign up the user to firebase using email and password. Sign in the user Sign out the user Also, I have ...
1 vote
1 answer
69 views

Managing file names in a file

The scenario here is to get a filename from the console and create it if it does not exist. I have two main questions; Is the way I used promises the best way? is there a better way? Here is my code;...
9 votes
2 answers
24k views

Check if images are loaded (ES6 Promises)

I wrote a small function that checks if an image or multiple images are loaded. For that purpose, I decided to use ES6 promises, but I'm not really sure if my way of handling errors is the best way. <...
2 votes
1 answer
260 views

Check RSS feed and post to Discord

I'm new to using JS for anything other than DOM manipulation, so I'm not sure if the following code is taking full advantage of the Async concept in JS. This is an example of a function I'm writing in ...
5 votes
1 answer
194 views

Resource closing in a promise chain

This is some code that fetches a result from a database. It connects, makes a query, processes the query, then has to close the DB (under all possible code paths) and return the result. It seems ...
2 votes
2 answers
70 views

Blog API implementation in node.js

This code is from my blog project. This project is almost done. This is working well. I can create new posts and update and display all saved posts. ...
4 votes
1 answer
1k views

Wrap async method in a way that the method is invoked only once for all calls that occur while the first of them is not resolved

Imagine we have a function that returns a Promise, ie call a GET endpoint of an api and return the response data. ...
1 vote
0 answers
39 views

Calling promise-returning function within promise-returning function

I am rather new to JavaScript and never really worked with promises before. My code works but I would like to learn if there is a better approach? I want to implement the following functionality: ...
1 vote
2 answers
456 views

Racing promises and consuming them in the order of their resolution time

The ideas are When multiple async calls are made, to be able to start consuming from the first resolving one regardless in what order the promises are fired. To construct a modern emitter of async ...
2 votes
1 answer
38 views

Typescript : Adding types to a function that takes in a string and returns a different promise based on the string

I have a function that takes in a string and based on the string hits different APIs to fetch images. I have solved it by writing an interface and then as the return type of the function, it returns a ...
1 vote
1 answer
61 views

Get images for PDFs from URLs

I Have the below code that gets urls of PDF files, send them to a convert function and returns them as images, is there a way to make this code more readable? Is there a way to avoid functions ...
1 vote
1 answer
2k views

NodeJS promise loop through all files in directory

I am trying to re-organise my mp3 collection based on its id3 meta data into folders based on the artist. I'm new to nodeJs and more importantly promises. I was hoping I could get some feedback on my ...
2 votes
2 answers
140 views

Mini JavaScript thread pool with maximum number of concurrently running tasks

I wrote this mini thread pool in JavaScript that takes a maximum number of concurrently running tasks and runs them in the order it was given. I appreciate any feedback or review. Thank you. ...
3 votes
1 answer
67 views

Starting with asynchronous JS and promises

I've learn to code almost alone, so I really need some ideas/advice, as it started to get really difficult to advance. Because this is mostly server side, I can't provide a running snippet, but yet it'...
1 vote
1 answer
4k views

Rewriting this function to use `promises` instead of `async: false`

Using parse.com's javascript API, I would like to get a variable number or images from img tags on a page and save those images in the currently logged in user's ...
8 votes
3 answers
3k views

await user input with async/await syntax

for clarity: moved here from stackoverflow after being pointed to Code Review being the better place for this question I love async/await and Promises since I got my hands on them. And I might be ...
2 votes
1 answer
2k views

Send message and wait for receive while using async/await and promises the proper way

I have this working code, but sendAndReceive function looks ugly/smelly to me. Eslint complains about using await inside a loop, and using ...
4 votes
2 answers
635 views

Passing data from one promise to another using then

I'm trying to get an object with ratings and titles properties: ...
3 votes
1 answer
64 views

Node.js package that retrieves data from an API, formats it and sends it out via email to a distribution list

I've created a Node.js package that retrieves data from Icinga (a monitoring platform), formats it and passes it off to a class that generates some HTML and then sends it all out as an email. The ...
4 votes
1 answer
1k views

Implementing Passport authentication with promises

Here is code implementing Passport authentication with a Google Strategy. It uses Mongoose to store and retrieve user data. You might need to be familiar with both of these technologies to review ...
3 votes
0 answers
58 views

Go language implementation of js promise static method

I try to implement the features of the js Promise using Go. Currently, I had implemented Promise.all(), Promise.allSettled() and ...
4 votes
1 answer
259 views

Correctly using promises with node-mysql

I have been trying to do a simple query and return the results with node-mysql however I had several problems. Originally I wrote it where there was no promise, but ...
-1 votes
1 answer
29 views

Am I using the same Typescript variable? [closed]

I am passing a in as a parameter and want to return b. This works, however I feel like it is wrong because I shouldn't have to ...
4 votes
1 answer
64 views

Input a web page with poker events, output a gcal compatible CSV file

This script takes input from poker tournament pages at pokeratlas dot com, and outputs a CSV file that I can import to Google Calendar, listing each of the tournament events, start time, location, and ...
2 votes
0 answers
596 views

Handling Promise that resolves but returns a 404

This is in a node and express API. I'm trying to figure out the best way to handle Promises that resolve, but return a 404 response. I have a method which uses node-fetch to make a POST call to update ...
5 votes
2 answers
2k views

Extending native JavaScript Promise with cancellation support

Updated, below is a more current and simple version of this. Also, if you track the progress of TC39's "ECMAScript Cancellation" proposal, this thread might be worth checking out. I'm ...
3 votes
0 answers
49 views

Optimisation potential when using deferred/promises and looping

I am fairly inexperienced when it comes to jQuery/JavaScript, so although the following code works, I am just looking to understand if my use of looping, deferred/promises etc could be optimised at ...
4 votes
1 answer
3k views

AngularJS recursive function call with $timeout

I have created a recursive function call in AngularJS and just wonder if is there a better way to solve this problem? The code works perfectly. My code is the following: ...
6 votes
2 answers
11k views

Pseudo Promise.all() polyfill

A few years back I interviewed with a company for a Javascript position. After a couple of warm-up challenges I was presented with this: Please write a function that calls back with ...
1 vote
1 answer
53 views

Promise-based HTTP abstraction layer

I am currently working in a project based on a microservices architecture pattern. Services are wired up by HTTP calls. They eventually call each others for fetching or putting some data. I am ...
8 votes
2 answers
756 views

Function to find user's region based on GPS coordinates

I've made an algorithm/ function to get a user's region based on their GPS coordinates. It primarily looks for big cites and counties for the region and the state for the outer region eg. orange ...
3 votes
1 answer
372 views

A thread-safe typed Promise implementation in Java for Android

Introduction I've created a typed Promise implementation in Java for Android, borrowing ideas from this article for a JavaScript implementation, by Forbes Lindesay. To allow for "asynchronicity", my ...
1 vote
1 answer
870 views

Implement jquery like functions addClass, removeClass and delay in Javascript

Assume $ is not the browser. Now have to implement $, it will take a string, which is a query, it will use the querySelector to select the element. (Reference: https://developer.mozilla.org/en-US/docs/...
10 votes
2 answers
498 views

Stack Exchange rev​iew queue notifications

A couple of days ago a user in chat asked us to spend more time in the queues. Kick starting my desire to get notifications for new items in the queues. Reviewing the queues has been something I've ...
0 votes
1 answer
97 views

Best approach on handling function that returns either a promise or just synchronous code [closed]

I wrote some code and I'm trying to get some feedback on it. I'll try to summerize the essential only. I have a function that based on a condition returns a promise or something else: ...
-1 votes
1 answer
485 views

JavaScript promise optional chaining [closed]

I've wrote a piece of code today that really make me sick about: ...
6 votes
1 answer
3k views

Asynchronous iterator for AngularJS

I wrote this as a convenient way to batch together multiple, repetitive AJAX calls. I was working in angular at the time, so I use the $q service, but I'm sure it ...
4 votes
1 answer
170 views

Implementing `Promise.all()`

I took a stab at implementing Promise.all(): ...
2 votes
1 answer
430 views

Is returning promise form angular service bad?

What is the problem when I return a promise from angular service instead of Observable? If it's a matter of any manipulation or side-effect, that I can easily do ...

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