Saving a variable within a for loop in JavaScript

Hey everyone, I could really use your help right now. Here's the code block I'm struggling with:

function readyToSubmit(answerPack, answerArr, len) {
  for (var i = 0; i < answerArr.length; i++) {
    var questionId = answerArr[i].id;
    console.log(questionId);

    // This is an asynchronous database operation
    userStore.getDoc(id).then(function(doc) {
      // When I try to log 'answerArr[i]' here, it shows up as undefined
      // I understand that it's because 'i' here refers to answerArr.length, so it ends up undefined
      // I want each questionId to be different, but it always ends up being the last one in the array
      // I know this is a closure issue, but I'm unsure how to solve it.

      doc.questionId = questionId; // always ends up being the same one
      answerPack.push(doc);
    });
  }
}

Can anyone guide me on how to achieve what I need in each iteration? I really appreciate any assistance you can provide. Thanks a lot! :)

javascriptfor-loopclosures

Answer №1

One possible approach is to:

function readyToSubmit(answerPack, answerArr, len) {
    for (var i = 0; i < answerArr.length; i++) {
        var questionId = answerArr[i].id;
        doasynch(questionId);
    }
}

function doasynch(questionId) {
    userStore.getDoc(id).then(function (doc) {
        doc.questionId = questionId;
        answerPack.push(doc);
    });
}

Further reading:

  1. Understanding JavaScript closures
  2. Dealing with closure inside loops

Similar questions

If you have not found the answer to your question or you are interested in this topic, then look at other similar questions below or use the search

Creating a 2D array matrix in JavaScript using a for loop and seamlessly continuing the number count onto the next row

I'm attempting to create a 2d matrix with numbers that continue onto the next row. var myMatrix = []; var rows = 5; var columns = 3; for (var i = 0; i < rows; i++) { var temp = 1; myMatrix[i] = [i]; for (var j = 0; j < columns; j++) ...

javascriptarraysfor-loopnested-loops

Rotating 3D cube with CSS, adjusting height during transition

I'm attempting to create a basic 2-sided cube rotation. Following the rotation, my goal is to click on one of the sides and have its height increase. However, I've run into an issue where the transition occurs from the middle instead of from the ...

javascriptjquerycss

The image slider is blocking the dropdown functionality of the navbar on mobile devices

My code is experiencing a conflict of events. I have created a menu bar using nav bar, as well as an image slider called the caroussel. The issue arises when the window is minimized - the menu bar fails to drop down properly with the presence of the caro ...

javascriptjqueryhtmlcsstwitter-bootstrap

Display the overlay solely when the dropdown is visible

My code works, but the 'overlay active' class only functions properly when I click on the button. If I click outside of the button, it doesn't work as intended. I want the 'overlay active' class to be displayed only when the dropd ...

javascriptjquerytwitter-bootstrapbootstrap-4

Issue with Angular.forEach loop malfunctioning

Here is the code for my custom filter that includes a parameter called viewbookoption, which is a dropdown value. Depending on the selected value from the dropdown, the data will be displayed in a grid. I have used a forEach loop in this filter, but it see ...

javascriptangularjs

Delete any fields that start with the name "XX"

Here is an example document extracted from a collection: { "teamAlpha": { }, "teamBeta": { }, "leader_name": "leader" } My goal is to remove all fields that begin with "team" from this document. Therefore, the expected outcome would be: {leader_name: "l ...

javascriptmongodbmongodb-query

Enhance Your Three.js Experience: Implementing Dots on Vertices

I am working with a wireframe sphere and looking to add dots to the vertices. Something similar to this image: https://i.sstatic.net/pzNO8.jpg. Below is all of my JavaScript code: var scene = new THREE.Scene(); var camera = new THREE.PerspectiveCamera( ...

javascriptthree.js

Issues with Converting JSON to HTML Table using JavaScript

Issues with Converting JSON to HTML Table Using JavaScript I've been trying to create a function that will display the contents of a JSON file in an HTML table. However, I keep getting an undefined error. Despite being able to see the data displayed ...

javascriptjqueryhtmljson

Evaluating substrings within a separate string using JavaScript

I need to compare two strings to see if one is a substring of the other. Below are the code snippets: var string1 = "www.google.com , www.yahoo.com , www.msn.com, in.news.yahoo.com"; var string2 = "in.news.yahoo.com/huffington-post-removes-sonia-gandh ...

javascript

Encountering a Typescript error while attempting to utilize mongoose functions

An example of a User interface is shown below: import {Document} from "mongoose"; export interface IUser extends Document{ email: string; password: string; strategy: string; userId: string; isValidPassword(password: string): ...

javascriptnode.jstypescriptexpressmongoose

ESLint detecting error with returning values in async arrow functions

Currently facing a minor inconvenience instead of a major problem. Here is the code snippet causing the issue: export const getLoginSession = async (req: NextApiRequest): Promise<undefined | User> => { const token = getTokenCookie(req) if (!t ...

javascripttypescript

Twice the data fetching through ajax on popup is observed using php mysql

I've been struggling for the past two hours. Attempted : location.reload(); reset form Tried many features, but after closing my popup and reopening it or opening another ID, the previous ID data is still visible. This happens continuously for all ...

javascriptphpjquerymysqlajax

Tips on choosing a child element with a parameter in React

Is it possible to pass a parameter in my function and use it to select a child of my JSON parse? I want to create a function (checkMatch) that can check if a username in my database matches with the input value. It should return 1 if there is a match, oth ...

javascriptjsonreactjsforeach

Error: The script is not found in the package.json configuration

I encountered the following error while trying to execute npm run dev: Error: Missing script: "dev" Error: Error: To view a list of available scripts, use the command: Error: npm run Here is a list of scripts present in my package.json file: "scripts ...

javascriptreactjsnpmnpm-scripts

What is the best way to apply a hover effect to a specific element?

Within my CSS stylesheet, I've defined the following: li.sort:hover {color: #F00;} All of my list items with the 'sort' class work as intended when the Document Object Model (DOM) is rendered. However, if I dynamically create a brand new ...

javascriptajaxmootools

Is it possible to update the value of Select2 as you type?

In my country, the majority of people do not have a Cyrillic keyboard on their devices. To address this issue, I created a function that converts Latin characters to Cyrillic in Select2's dropdown for easier city selection. However, I noticed that the ...

javascriptjqueryjquery-select2

`How can I retrieve a PHP variable using a JavaScript AJAX request?`

When sending an AJAX request, I encounter a situation where: //javascript var rq = new XMLHTTPrequest(); rq.open('POST','test.php', true); rq.send(JSONString); Within "test.php" file, the following action is taken: //php $data = "Hel ...

javascriptphpajax

Running pug directly from the local node_modules directory

I'm currently attempting to run pug (/jade) from my node_modules directory, however I am unable to locate the executable within the node_modules/.bin folder. I am running MacOS 10.12.5 and installed pug using the "npm install --save pug" command. Is ...

javascriptnode.jsnpmpug

Laravel is unable to interpret formData

I've been on a quest to find answers, but so far I'm coming up empty. I'm trying to send file input to a Laravel controller via Ajax, but it seems like the controller can't read the data at all. Here is my Ajax code: let fd = n ...

javascriptphpjqueryajaxlaravel

python extract values from a JSON object

I've been searching everywhere, but I haven't been able to find a solution. It seems like my question is not clear enough, so I'm hoping to receive some guidance. Currently, I am working with turbogears2.2. In my client view, I am sending a ...

javascriptpythonjsondictionaryturbogears2