From b7f8749cdfbd01d19a71d560f5c8b4322f11542e Mon Sep 17 00:00:00 2001
From: Aditya Telange <21258296+adityatelange@users.noreply.github.com>
Date: Fri, 18 Dec 2020 11:45:10 +0530
Subject: [PATCH] Search: Keyboard Bindings for easier navigation (#138)

* set up basic actions on keypress
* add actions to perform conditionally
* add simple highlight animation
* prevent mouseclick to change active element
* clear input box on Escape
* click on Arrow Right
* clear results and focus search-input on esc
* refactor
---
 assets/css/search.css        |  8 +++--
 assets/js/fastsearch.js      | 66 ++++++++++++++++++++++++++++++++++--
 layouts/_default/search.html |  2 +-
 3 files changed, 71 insertions(+), 5 deletions(-)

diff --git a/assets/css/search.css b/assets/css/search.css
index d788cd22..275cbe10 100644
--- a/assets/css/search.css
+++ b/assets/css/search.css
@@ -1,4 +1,4 @@
-.searchbox input {
+#searchbox input {
     padding: 4px 10px;
     width: 100%;
     color: var(--primary);
@@ -7,7 +7,7 @@
     border-radius: var(--radius);
 }
 
-.searchbox input:focus {
+#searchbox input:focus {
     border-color: var(--secondary);
 }
 
@@ -38,3 +38,7 @@
     left: 0px;
     outline: none;
 }
+
+#searchResults .active {
+    transform: scale(.98);
+}
diff --git a/assets/js/fastsearch.js b/assets/js/fastsearch.js
index e76f9193..152d31c1 100644
--- a/assets/js/fastsearch.js
+++ b/assets/js/fastsearch.js
@@ -1,4 +1,8 @@
 var fuse; // holds our search engine
+var resList = document.getElementById('searchResults');
+var sInput = document.getElementById('searchInput');
+var first, last = null
+var resultsAvailable = false;
 
 // load our search index, only executed onload
 function loadSearch() {
@@ -35,6 +39,15 @@ function loadSearch() {
     xhr.send();
 }
 
+
+function itemGen(name, link) {
+    return `<li class="post-entry"><header class="entry-header">${name}&nbsp;»</header><a href="${link}" aria-label="${name}"></a></li>`
+}
+
+function activeToggle() {
+    document.activeElement.parentElement.classList.toggle("active")
+}
+
 // execute search as each character is typed
 document.getElementById("searchInput").onkeyup = function (e) {
     // run a search query (for "term") every time a letter is typed
@@ -50,11 +63,60 @@ document.getElementById("searchInput").onkeyup = function (e) {
         }
 
         document.getElementById("searchResults").innerHTML = resultSet;
+        resultsAvailable = true;
+        first = resList.firstChild;
+        last = resList.lastChild;
     } else {
+        resultsAvailable = false;
         document.getElementById("searchResults").innerHTML = '';
     }
 }
 
-function itemGen(name, link) {
-    return `<li class="post-entry"><header class="entry-header">${name}&nbsp;»</header><a href="${link}" aria-label="${name}"></a></li>`
+// kb bindings
+document.onkeydown = function (e) {
+    let key = e.key;
+    let ae = document.activeElement;
+
+    if (key === "ArrowDown" && resultsAvailable) {
+        e.preventDefault();
+        if (ae == sInput) {
+            // if the currently focused element is the search input, focus the <a> of first <li>
+            activeToggle(); // rm active class
+            resList.firstChild.lastChild.focus();
+            activeToggle(); // add active class
+        } else if (ae.parentElement == last) {
+            // if the currently focused element's parent is last, do nothing
+        } else {
+            // otherwise select the next search result
+            activeToggle(); // rm active class
+            ae.parentElement.nextSibling.lastChild.focus();
+            activeToggle(); // add active class
+        }
+    } else if (key === "ArrowUp" && resultsAvailable) {
+        e.preventDefault();
+        if (ae == sInput) {
+            // if the currently focused element is input box, do nothing
+        } else if (ae.parentElement == first) {
+            // if the currently focused element is first item, go to input box
+            activeToggle(); // rm active class
+            sInput.focus();
+        } else {
+            // otherwise select the previous search result
+            activeToggle(); // rm active class
+            ae.parentElement.previousSibling.lastChild.focus();
+            activeToggle(); // add active class
+        }
+    } else if (key === "ArrowRight" && resultsAvailable) {
+        ae.click(); // click on active link
+    } else if (key === "Escape") {
+        resultsAvailable = false;
+        document.getElementById("searchResults").innerHTML = sInput.value = ''; // clear inputbox and searchResults
+        sInput.focus(); // shift focus to input box
+    }
+}
+
+document.onmousedown = function (e) {
+    if (e.type === "mousedown") {
+        e.preventDefault(); // prevent mousedown to change focus
+    }
 }
diff --git a/layouts/_default/search.html b/layouts/_default/search.html
index 44b72c57..2105c298 100644
--- a/layouts/_default/search.html
+++ b/layouts/_default/search.html
@@ -30,7 +30,7 @@
     {{- end}}
 </header>
 
-<div class="searchbox">
+<div id="searchbox">
     <input id="searchInput" autofocus placeholder="{{.Title}} ↵" aria-label="search">
     <ul id="searchResults" aria-label="search results"></ul>
 </div>