How to correctly calculate pagination in JavaScript?

Question

JavaScript

Hello.
-
It seems to be a simple question, but I have not found a solution.
For example, in the function I set the parameter = 10
Does this mean that the script considers json nesting? and finds that there are 55 "records"
As a result, he somehow breaks these 55 like this
---
10
10
10
10
10
5

Then through Array.prototype.slice()I just get parts of this json, and some kind of pagination is obtained. Perhaps you will say that I am doing nonsense, you can install a ready-made solution via npm or yarn and I will be happy. But I really need to understand how you can split a different number of records into the number of "portions" that I set, maybe at a time I will display not 10 but 5 or 8 records.
Actually, the question is:
How can I split any number of records into a parameter of any number of portions, so that I can then get these pieces and calculate how many pagination buttons I will have?
It would be convenient to receive it in the form of an array.

Answer 1

const data = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
const itemsPerPage = 3; // элементов на странице

const pages = data.reduce((all, page, i) => {
   const ch = Math.floor(i / itemsPerPage); 
   all[ch] = [].concat((all[ch] || []),  page); 
   return all;
}, []);

console.log(pages);