trainee | This project was bootstrapped with Create React App | Frontend Framework library

I am trying to dynamically write data(in JavaScript)inside my HTML table, but haven't been able to thrive so far. I am relatively new to frontend, especially JS. I would highly appreciate any suggestion on how to get this to function properly. I have tried .innerHTML method, .innerText etc, but no good to show for it. Here's my index.html and app.js files, so anybody can look into it. Thank you soo much in advance!

HTML code:

I am using pixellib fot training custom image instance segmentation. I have created a dataset whiche can be seen below in link. Dataset:https://drive.google.com/drive/folders/1MjpDNZtzGRNxEtCDcTmrjUuB1ics_3Jk?usp=sharing the code which I used to make a custom model is

I am trying to get the second last value in each row of a data frame, meaning the first job a person has had. (Job1_latest is the most recent job and people had a different number of jobs in the past and I want to get the first one). I managed to get the last value per row with the code below:

first_job <- function(x) tail(x[!is.na(x)], 1)

first_job <- apply(data, 1, first_job)

I'm having an error between sending a JSON POST request to my C# .NET backend controller, which gives me a POST error code 400, which I understand to mean bad request. I prompt the user (a fitness trainer at a gym) for information for a new training session, which looks like this (extra code removed for concision):

I'm working on a Rails + React web app. And there's one GET request which needs a parameter trainee_id.

My question is:

Do I need to add params.require(:trainee_id) and relative exception handler to verify the existence of the parameter?

Route: GET /results/trainees/:trainee_id/published

How to keep text fields to stay hidden by default when the page is loaded? But, show up when a relevant drop down option is selected. The javascript works to some extent. But, I want to keep the input fields hidden initially.

I am receiving a json object from my API and I am pushing it into my state. That object has a field called "grades". That grades is an array of objects that have a field called "mark".

I would like to take the "mark" from all the objects and push it into a new array / state in order to calculate the average "mark".

Here's my code that includes comments on what I would like to do:

I have for example this dataset:

How to hide or unhide table rows containing form fields in a php website based on a drop down selection using jquery/ ajax? I am stuck on this. I used the script below but, it only hides the field leaving blank rows between the form fields. So, is there a way to also hide the respective table rows.

Thank you.

my code: