Adding Full Absolute URLs to the Anchor Links in the Navbar that are not on the same page. Works best with the parent menu and sub-menu links in the navbar. And for WordPress navbar especially.

AbsoluteAnchorLinksToOtherPages.js

/**
 * Adding Full Absolute URLs to the Anchor Links in the Navbar that are not
 * on the same page. Works best with the parent menu and sub-menu
 * links in the navbar. And for WordPress navbar especially. 
 *
 * Replace #parent_links_selector with the parent links selector
 */
jQuery(document).ready(function($) {

  $('#parent_links_selector').each(function(i, el) {

    var $el = $(el),
        elHref = $el.attr('href'),
        pathname = document.location.pathname;

    if ( elHref.indexOf( pathname.slice(0,-1) ) < 0 ) {

      $el.siblings('.sub-menu').find('a[href^="#"]').each(function(i, el) {
        $(el).attr('href', function(i, href) {
          return elHref + href;
        });
      }).on('click', function() {
        return true;
      });

    }
      
  });
  
});