JavaScript's concept of nesting arrays of arrays of objects provides a powerful way

Question

JavaScript's concept of nesting arrays of arrays of objects provides a powerful way

I'm encountering a TypeError saying testsession.testset[0].athletes is undefined. I've tried various approaches but still facing this issue. Is it not feasible to have an array of arrays of objects?

var testsession = {};
var testsetname = {};
var testset = [];
testsession.testsetname = testsetname;
testsession.testsetname = "week9";
testsession.testset = testset;
testsession.testset.push("400M");
testsession.testset.push("800M");

var athletes = [];
var Time = "49.2";
var AthleteID = "a92";
var athlete = { "AthleteID": AthleteID, "Time": Time};
//console.log(pointer);
testsession.testset[0].athletes = athletes;
testsession.testset[0].athletes.push(athlete)
console.log(testsession.testset[0].athletes[0]);

javascript arrays

Answer 1

Answer №1

The initial testset[0] value is stored as a string, let's convert it into an object

var testsession = {};
var testsetname = {};
var testset = [];
testsession.testsetname = testsetname;
testsession.testsetname = "week9";
testsession.testset = testset;

//Previously, a direct push of '400m' was causing errors due to being a string
testsession.testset.push({distance: "400M"});
testsession.testset.push({distance: "800M"});

var athletes = [];
var Time = "49.2";
var AthleteID = "a92";
var athlete = { "AthleteID": AthleteID, "Time": Time};
//console.log(pointer);
testsession.testset[0].athletes = athletes;
testsession.testset[0].athletes.push(athlete)
console.log(testsession.testset[0].athletes[0]);

Answer 2

The initial testset[0] value is stored as a string, let's convert it into an object

var testsession = {};
var testsetname = {};
var testset = [];
testsession.testsetname = testsetname;
testsession.testsetname = "week9";
testsession.testset = testset;

//Previously, a direct push of '400m' was causing errors due to being a string
testsession.testset.push({distance: "400M"});
testsession.testset.push({distance: "800M"});

var athletes = [];
var Time = "49.2";
var AthleteID = "a92";
var athlete = { "AthleteID": AthleteID, "Time": Time};
//console.log(pointer);
testsession.testset[0].athletes = athletes;
testsession.testset[0].athletes.push(athlete)
console.log(testsession.testset[0].athletes[0]);

Answer 3

Answer №2

sessionData.sessionArray[0] is a simple value, specifically a string.

This means that the following line of code will not produce the expected outcome:

sessionData.sessionArray[0].players = players;

What occurs in this situation? The primitive on the left doesn't have a players property, so JavaScript transforms it into a String object before adding the property. However, this temporary String object eventually vanishes.

Therefore, it's as if the assignment never happened: sessionData.testset[0] will retain its original primitive value, which does not support additional properties.

If you attempt to access the players property later on, the same process unfolds: JavaScript converts it into a String object and realizes there's no players property available, resulting in the return of undefined.

Answer 4

sessionData.sessionArray[0] is a simple value, specifically a string.

This means that the following line of code will not produce the expected outcome:

sessionData.sessionArray[0].players = players;

What occurs in this situation? The primitive on the left doesn't have a players property, so JavaScript transforms it into a String object before adding the property. However, this temporary String object eventually vanishes.

Therefore, it's as if the assignment never happened: sessionData.testset[0] will retain its original primitive value, which does not support additional properties.

If you attempt to access the players property later on, the same process unfolds: JavaScript converts it into a String object and realizes there's no players property available, resulting in the return of undefined.

Answer 5

Answer №3

If you attempt to retrieve the value of testsession.testset[0], it will be returned as a string. To ensure correct functionality, consider initializing testsession.testset[0] = {}; before attempting to access any of its properties.

Answer 6

If you attempt to retrieve the value of testsession.testset[0], it will be returned as a string. To ensure correct functionality, consider initializing testsession.testset[0] = {}; before attempting to access any of its properties.

Answer 7

Answer №4

It seems like you've got the code working just fine!

<script >

var testsession = {};
testsession.testset = [];
testsession.testset.push({testsetname:"week9"});
testsession.testset[0].list = [];

testsession.testset[0].list.push({distance:"400M"});
testsession.testset[0].list[0].athletes = [];
testsession.testset[0].list[0].athletes.push({ AthleteID:  "a92", Time: "49.2"});

testsession.testset[0].list.push({distance:"900M"});
testsession.testset[0].list[1].athletes = [];
testsession.testset[0].list[1].athletes.push({ AthleteID:  "a93", Time: "99.2"});

console.log(testsession);

</script>

Here's the expected output:

"{"testset":[{"testsetname":"week9","list":[{"distance":"400M","athletes":[{"AthleteID":"a92","Time":"49.2"}]},{"distance":"900M","athletes":[{"AthleteID":"a93","Time":"99.2"}]}]}]}"

https://i.sstatic.net/ImmLn.png

Answer 8

It seems like you've got the code working just fine!

<script >

var testsession = {};
testsession.testset = [];
testsession.testset.push({testsetname:"week9"});
testsession.testset[0].list = [];

testsession.testset[0].list.push({distance:"400M"});
testsession.testset[0].list[0].athletes = [];
testsession.testset[0].list[0].athletes.push({ AthleteID:  "a92", Time: "49.2"});

testsession.testset[0].list.push({distance:"900M"});
testsession.testset[0].list[1].athletes = [];
testsession.testset[0].list[1].athletes.push({ AthleteID:  "a93", Time: "99.2"});

console.log(testsession);

</script>

Here's the expected output:

"{"testset":[{"testsetname":"week9","list":[{"distance":"400M","athletes":[{"AthleteID":"a92","Time":"49.2"}]},{"distance":"900M","athletes":[{"AthleteID":"a93","Time":"99.2"}]}]}]}"

https://i.sstatic.net/ImmLn.png

JavaScript's concept of nesting arrays of arrays of objects provides a powerful way

Answer №1

Answer №2

Answer №3

Answer №4

Similar questions

Why does NPM keep flagging dependencies as unmet even though they are clearly installed and met?

Display a notification badge using Firestore

Issues with jQuery custom accordion functionality in Internet Explorer, Safari, and Chrome browsers

Using Rails 5 and Ajax: Comments will only be appended if a comment already exists

Executing a series of tests using Postman

Retrieving Form Values from Child Components in React upon Submission

Getting response header data in Next.js is a piece of cake!

I am experiencing an issue where the submit button in my HTML form is unresponsive to clicks

Another method to verify an input using HTML5 regex and JavaScript

Advantages of using individual CSS files for components in React.js

Looking to merge two components into one single form using Angular?

I require assistance in computing the total number of subordinate tags present within KML files

use a jQuery function to submit a form

Is AngularJS really as safe as they claim?

react component fails to rerender upon state change

Unset a random element within a multidimensional array if a specific key-value pair is present

Ensuring an element matches the height of its child using CSS styling

Create an array of references

Using PHP, jQuery, and HTML to submit a form and insert data into MySQL, all while

Retrieve the user-inputted data from an Electron BrowserView's input field