To automatically scroll a webpage with javascript, you can use the setInterval() function to repeatedly trigger a scrolling function.

(function (document) {
  'use strict';
  const ready = (callback) => {
    if (document.readyState != 'loading') callback();
    else document.addEventListener('DOMContentLoaded', callback);
  };
  ready(() => {
    const target = document.body.scrollHeight - window.innerHeight;
    const duration = 45000;
    const distance = target / Math.floor(duration / 45);
    const interval = setInterval(function () {
      if (window.pageYOffset >= target) clearInterval(interval);
      else window.scrollBy(0, distance);
    }, 45);
  });
})(document);