From a8c4f887e5fe4426df825aa39648a3fff2231416 Mon Sep 17 00:00:00 2001
From: George Cushen <gcushen@users.noreply.github.com>
Date: Thu, 11 Jul 2019 20:54:52 +0100
Subject: [PATCH] fix: navbar active link highlighting and scrolling

Fixes some edge cases caused due to responsive navbar height and dynamic
Portfolio widget height, as well as case where offset was non-integer,
requiring float to be rounded up.

Fix #1199
---
 assets/js/academic.js        | 31 +++++++++++++++++++++----------
 layouts/_default/baseof.html |  2 +-
 2 files changed, 22 insertions(+), 11 deletions(-)

diff --git a/assets/js/academic.js b/assets/js/academic.js
index b0d01c1f..69d21367 100644
--- a/assets/js/academic.js
+++ b/assets/js/academic.js
@@ -11,9 +11,13 @@
    * Responsive scrolling for URL hashes.
    * --------------------------------------------------------------------------- */
 
-  // Dynamically get responsive navigation bar offset.
-  let $navbar = $('.navbar');
-  let navbar_offset = $navbar.innerHeight();
+  // Dynamically get responsive navigation bar height for offsetting Scrollspy.
+  function getNavBarHeight() {
+    let $navbar = $('.navbar');
+    let navbar_offset = $navbar.innerHeight();
+    console.debug('Navbar height: ' + navbar_offset);
+    return navbar_offset;
+  }
 
   /**
    * Responsive hash scrolling.
@@ -30,9 +34,10 @@
 
     // If target element exists, scroll to it taking into account fixed navigation bar offset.
     if($(target).length) {
+      let elementOffset = Math.ceil($(target).offset().top - getNavBarHeight());  // Round up to highlight right ID!
       $('body').addClass('scrolling');
       $('html, body').animate({
-        scrollTop: $(target).offset().top - navbar_offset
+        scrollTop: elementOffset
       }, 600, function () {
         $('body').removeClass('scrolling');
       });
@@ -46,7 +51,7 @@
     let $body = $('body');
     let data = $body.data('bs.scrollspy');
     if (data) {
-      data._config.offset = navbar_offset;
+      data._config.offset = getNavBarHeight();
       $body.data('bs.scrollspy', data);
       $body.scrollspy('refresh');
     }
@@ -77,8 +82,15 @@
 
       // Use jQuery's animate() method for smooth page scrolling.
       // The numerical parameter specifies the time (ms) taken to scroll to the specified hash.
+      let elementOffset = Math.ceil($(hash).offset().top - getNavBarHeight());  // Round up to highlight right ID!
+
+      // Uncomment to debug.
+      // let scrollTop = $(window).scrollTop();
+      // let scrollDelta = (elementOffset - scrollTop);
+      // console.debug('Scroll Delta: ' + scrollDelta);
+
       $('html, body').animate({
-        scrollTop: $(hash).offset().top - navbar_offset
+        scrollTop: elementOffset
       }, 800);
     }
   });
@@ -446,6 +458,9 @@
    * --------------------------------------------------------------------------- */
 
   $(window).on('load', function() {
+    // Re-initialize Scrollspy with dynamic navbar height offset.
+    fixScrollspy();
+
     if (window.location.hash) {
       // When accessing homepage from another page and `#top` hash is set, show top of page (no hash).
       if (window.location.hash == "#top") {
@@ -459,10 +474,6 @@
       }
     }
 
-    // Initialize Scrollspy.
-    let $body = $('body');
-    $body.scrollspy({offset: navbar_offset });
-
     // Call `fixScrollspy` when window is resized.
     let resizeTimer;
     $(window).resize(function() {
diff --git a/layouts/_default/baseof.html b/layouts/_default/baseof.html
index 107ee5d7..49332629 100644
--- a/layouts/_default/baseof.html
+++ b/layouts/_default/baseof.html
@@ -3,7 +3,7 @@
 
 {{ partial "site_head.html" . }}
 
-<body id="top" data-spy="scroll" data-target="{{ if or .IsHome (eq .Type "widget_page") }}#navbar-main{{else}}#TableOfContents{{end}}" data-offset="70" {{ if not (.Scratch.Get "light") }}class="dark"{{end}}>
+<body id="top" data-spy="scroll" data-target="{{ if or .IsHome (eq .Type "widget_page") }}#navbar-main{{else}}#TableOfContents{{end}}" {{ if not (.Scratch.Get "light") }}class="dark"{{end}}>
 
   {{ partial "search" . }}