Guys how can I access, manipulate and use my HTML element from express as backend?

See more:

Javascript

HTML

DOM

Node.js

, +

I'm tryingto send or post the checkbox element below to express that act as the backend of my app, in my case from the app.js to index.js(express).


APP.JS file

const checkbox = document.createElement("checkbox");

checkbox.innerHTML = `
       <label class="checkbox" for="myCheckboxId">
         <input class="checkbox__input" type="checkbox" name="myCheckboxName" id="myCheckboxId">
         <div class="checkbox__box"></div>
       </label>
       `;

The visualization in the browser is good but then I need to do some manipulation in index.js express file so that I can add this element into a column table (that it is filled in express file). The value of a checkbox variable in index.js file should be the same element of that in app.js file. I understand that in node/express it is not possible to use the "document." element. So how can I reach my objective?

What I have tried:

Tried to use fetch API but got only undefined values (maybe using that wrong)
Tried to check jsdom or other similar tools but these were not useful for my objectve.