Cacher is the code snippet organizer for pro developers

let chapters = parseInt((document.querySelectorAll('h1 span')[0].innerText).replace(RegExp('Chapter ','g'), '')) - 1
let sections = (window.pageYOffset + window.innerHeight) / document.getElementsByTagName("body")[0].scrollHeight

console.log(( (chapters + sections) / 21 * 100 ).toFixed(1))