html:
<div id="array"></div>
App 1: inserts data into a html div
document.getElementById('array').innerText = data;
App 2: takes data from html
let new_data = document.getElementById('array').innerText
Is it possible to turn new_data into an array and if so how?
with new_data, you can use .innerText/.textContent/.innerHTML, whichever works to your liking to get the content inside, and then, since it is a string, you can just use .split() if you wish to split it. If the content is a JSON object, you can use JSON.parse(the_string_here) to get a JSON object / Array from a string into the respective object.
If that doesn't help, could you share what the content of the html div looks like, so I could get a better understanding of what you're trying to accomplish?
You can simply take a storage variable and push the values from the div into it.
A simple example, which you probably still have to adjust.
const storage = []
document.getElementById('array').innerText = 'Hello';
storage.push( document.getElementById('array').innerText )
let newData = document.getElementById('array').innerText = document.getElementById('array').innerText + ' World';
storage.push(newData)
console.log(storage)<div id="array"></div>