Locate the pagination element on a webpage

find-pagination.js

/*
Function to find the pagination element on a webpage
with reasonable accuracy.
*/

function findPagination() {
  const pagElem =
  Array.from(document.querySelectorAll('body *'))
  .filter(el => el.nodeType === 1 && el.nodeName !== 'SCRIPT')
  .filter(el => el.innerHTML.match(/>[\t\n\r\s]*\d[\t\n\r\s]*</g) !== null )
  .filter(el => el.innerHTML.match(/>[\t\n\r\s]*\d[\t\n\r\s]*</g).length > 1)
  .filter((el, i, arr) => !arr.some(e => Array.from(el.children).includes(e)))
  .pop();
  if (pagElem) {
    return pagElem
  } else {
    return null
  }
}

/*
Some functions to help extract useful information
from the pagination element on a page
*/

// array with the visible page numbers
function findIntsInElement(elem) {
  const html = elem.innerHTML
  return [...html.matchAll(/>[\t\n\r\s]*(\d+)[\t\n\r\s]*</g)]
    .map(n => n.pop())
}

function findFloatsInElement(elem) {
  const html = elem.innerHTML
  return [...html.matchAll(/>[\t\n\r\s]*(\d+[\.,]?\d+)[\t\n\r\s]*</g)]
    .map(n => n.pop())
}

function findLastChildWithNumber(elem) {
  const childElems = Array.from(elem.children)
  return childElems.filter(node => node.nodeType === 1)
  .reverse().find(el => /\d+/.test(el.innerText))
}

function findFirstSiblingWithTag(tag) {
  return (elem) => {
    while (!elem.nextElementSibling) {
      elem = elem.parentNode
    }
    const sib = elem.nextElementSibling
    if (sib.nodeName === tag) {
      return sib
    } else {
      return sib.querySelector(tag)
    }
  }
}

// helper for finding next-page buttons
const findFirstLinkSibling = (elem) => findFirstSiblingWithTag('A')(elem)