Simulate browsers' scroll-to-anchor behavior on page load.

anchor.js

(function() {
  function hashchange() {
    if (!location.hash) {
      return;
    }
    // Don't do anything if the current target exists.
    if (document.querySelector(":target")) {
      return;
    }
    var name = "user-content-" + decodeURIComponent(location.hash.slice(1));
    var target = document.getElementById(name) || document.getElementsByName(name)[0];
    if (target != null) {
      target.scrollIntoView();
    }
  }

  // Scroll to anchor when clicked on page.
  window.addEventListener('hashchange', function() {
    hashchange();
  });

  // Scroll to anchor on page load.
  $(function() {
    hashchange();
  });
}).call(this);