Paginator algorithm

paginator.js

// converted to JS from this python solution: https://stackoverflow.com/a/40116188/1408053

const window = 5;
let start = page - window
let end = page + window

if (start <= 0) {
  end = end - start + 1
  start = 1
}
if (end > totalPages) {
  end = totalPages
  start = Math.max(end - (window * 2) + 1, 1)
}