Fixed sticky title and author hover JS (#629)

no issue

- replaces author hover JS that was lost during merge
- replaces `floating-header.js` with `sticky-nav-title.js` containing the relevant JS that was lost during merge with a cleanup for unused variables and unnecessary event listeners
- removes reference to non-existent `{{> floating-header}}` partial

assets/js/floating-header.js

@@ -1,73 +0,0 @@
-/* eslint-env browser */
-
-/**
- * Floating header
- * Used on invividual post pages, displays a sticky header with progress indicator
- *
- * This JS is automatically applied for any template where you use the
- * {{> floating-header}} partial
- */
-
-(function (window, document) {
-    // set up Casper as a global object
-    if (!window.Casper) {
-        window.Casper = {};
-    }
-
-    window.Casper.floatingHeader = function floatingHeader() {
-        // NOTE: Scroll performance is poor in Safari
-        // - this appears to be due to the events firing much more slowly in Safari.
-        //   Dropping the scroll event and using only a raf loop results in smoother
-        //   scrolling but continuous processing even when not scrolling
-
-        var progressBar = document.querySelector('#reading-progress');
-        var header = document.querySelector('.floating-header');
-        var title = document.querySelector('.post-full-title');
-
-        var lastScrollY = window.scrollY;
-        var lastWindowHeight = window.innerHeight;
-        var lastDocumentHeight = document.body.clientHeight;
-        var ticking = false;
-
-        function onScroll() {
-            lastScrollY = window.scrollY;
-            requestTick();
-        }
-
-        function onResize() {
-            lastWindowHeight = window.innerHeight;
-            lastDocumentHeight = document.body.clientHeight;
-            requestTick();
-        }
-
-        function requestTick() {
-            if (!ticking) {
-                requestAnimationFrame(update);
-            }
-            ticking = true;
-        }
-
-        function update() {
-            var trigger = title.getBoundingClientRect().top + window.scrollY;
-            var triggerOffset = title.offsetHeight + 35;
-            var progressMax = lastDocumentHeight - lastWindowHeight;
-
-            // show/hide floating header
-            if (lastScrollY >= trigger + triggerOffset) {
-                header.classList.add('floating-active');
-            } else {
-                header.classList.remove('floating-active');
-            }
-
-            progressBar.setAttribute('max', progressMax);
-            progressBar.setAttribute('value', lastScrollY);
-
-            ticking = false;
-        }
-
-        window.addEventListener('scroll', onScroll, {passive: true});
-        window.addEventListener('resize', onResize, false);
-
-        update();
-    };
-})(window, document);

assets/js/sticky-nav-title.js

@@ -0,0 +1,61 @@
+/* eslint-env browser */
+
+/**
+ * Nav/Title replacement
+ * Used on invividual post pages, displays the post title in place of the nav
+ * bar when scrolling past the title
+ *
+ * Usage:
+ * ```
+ * Casper.stickyTitle({
+ *     navSelector: '.site-nav-main',
+ *     titleSelector: '.post-full-title',
+ *     activeClass: 'nav-post-title-active'
+ * });
+ * ```
+ */
+
+(function (window, document) {
+    // set up Casper as a global object
+    if (!window.Casper) {
+        window.Casper = {};
+    }
+
+    window.Casper.stickyNavTitle = function stickyNavTitle(options) {
+        var nav = document.querySelector(options.navSelector);
+        var title = document.querySelector(options.titleSelector);
+
+        var lastScrollY = window.scrollY;
+        var ticking = false;
+
+        function onScroll() {
+            lastScrollY = window.scrollY;
+            requestTick();
+        }
+
+        function requestTick() {
+            if (!ticking) {
+                requestAnimationFrame(update);
+            }
+            ticking = true;
+        }
+
+        function update() {
+            var trigger = title.getBoundingClientRect().top + window.scrollY;
+            var triggerOffset = title.offsetHeight + 35;
+
+            // show/hide post title
+            if (lastScrollY >= trigger + triggerOffset) {
+                nav.classList.add(options.activeClass);
+            } else {
+                nav.classList.remove(options.activeClass);
+            }
+
+            ticking = false;
+        }
+
+        window.addEventListener('scroll', onScroll, {passive: true});
+
+        update();
+    };
+})(window, document);