Search: Add UI, elasticlunr.js, demo by indexing current page

src/theme/book.css

@@ -151,11 +151,12 @@ table thead td {
   max-width: 100%;
 }
 .menu-bar {
-  position: relative;
   height: 50px;
+  display: flex;
+  justify-content: space-between;
+  align-items: baseline;
 }
 .menu-bar i {
-  position: relative;
   margin: 0 10px;
   z-index: 10;
   line-height: 50px;
@@ -174,16 +175,29 @@ table thead td {
 .menu-bar .right-buttons {
   float: right;
 }
+#searchbar {
+  border: 1px solid #BBB;
+  border-radius: 3px;
+  padding: 3px 5px;
+  width: 50px;
+  transition: width 0.5s ease-in-out;
+}
+#searchbar:focus, #searchbar:hover, #searchbar.active {
+  width: 150px;
+}
+.searchresults-header {
+  font-weight: bold;
+  font-size: 1em;
+}
+.searchresults-outer {
+  border-bottom: 1px dashed #CCC;
+  display: none;
+}
 .menu-title {
-  display: inline-block;
+  display: inline;
   font-weight: 200;
   font-size: 20px;
   line-height: 50px;
-  position: absolute;
-  top: 0;
-  left: 0;
-  right: 0;
-  bottom: 0;
   text-align: center;
   margin: 0;
   opacity: 0;
@@ -924,7 +938,9 @@ table thead td {
   #sidebar,
   #menu-bar,
   .nav-chapters,
-  .mobile-nav-chapters {
+  .mobile-nav-chapters,
+  #searchbar,
+  #search-go {
     display: none;
   }
   #page-wrapper {

src/theme/book.js

@@ -38,11 +38,13 @@ $( document ).ready(function() {
 
     var KEY_CODES = {
         PREVIOUS_KEY: 37,
-        NEXT_KEY: 39
+        NEXT_KEY: 39,
+        SEARCH_KEY: 83
     };
 
     $(document).on('keydown', function (e) {
         if (e.altKey || e.ctrlKey || e.metaKey || e.shiftKey) { return; }
+        if ($('#searchbar').is( ":focus" )) { return; }
         switch (e.keyCode) {
             case KEY_CODES.NEXT_KEY:
                 e.preventDefault();
@@ -56,6 +58,10 @@ $( document ).ready(function() {
                     window.location.href = $('.nav-chapters.previous').attr('href');
                 }
                 break;
+            case KEY_CODES.SEARCH_KEY:
+                e.preventDefault();
+                $('#searchbar').focus();
+                break;
         }
     });
 
@@ -82,6 +88,81 @@ $( document ).ready(function() {
         sidebar.scrollTop(activeSection.offset().top);
     }
 
+    // For testing purposes: Index current page
+    var searchindex = create_text_searchindex();
+    var current_searchterm = "";
+    var teaser_size_half = 80;
+
+    // Searchbar
+    $("#searchbar").on('keyup', function (e) {
+        var display = $('#searchresults');
+        var outer = $("#searchresults-outer");
+
+        var searchterm = e.target.value.trim();
+        if (searchterm != "") {
+            // keep searchbar expanded
+            $(e.target).addClass("active");
+
+            // Don't search twice the same
+            if (current_searchterm == searchterm) { return; }
+            else { current_searchterm = searchterm; }
+
+            // Do the actual search
+            var results = searchindex.search(searchterm, {
+                bool: "AND",
+                expand: true
+            });
+
+            // Display search metrics
+            var searchheader = "";
+            if (results.length > 0) {
+                searchheader = results.length + " search results for '" + searchterm + "':";
+            } else if (results.length == 1) {
+                searchheader = results.length + " search result for '" + searchterm + "':";
+            } else {
+                searchheader = "No search results for '" + searchterm + "'.";
+            }
+            $('#searchresults-header').text(searchheader);
+
+            // Clear and insert results
+            var firstterm = searchterm.split(' ')[0];
+            display.empty();
+            for(var i = 0, size = results.length; i < size ; i++){
+                var result = results[i];
+                document.lsd = result.doc;
+                var firstoccurence = result.doc.body.search(firstterm);
+                var teaser = "";
+                if (firstoccurence != -1) {
+                    var teaserstartindex = firstoccurence - teaser_size_half;
+                    var nextwordindex = result.doc.body.indexOf(" ", teaserstartindex);
+                    if (nextwordindex != -1) {
+                        teaserstartindex = nextwordindex;
+                    }
+                    var teaserendindex = firstoccurence + teaser_size_half;
+                    nextwordindex = result.doc.body.indexOf(" ", teaserendindex);
+                    if (nextwordindex != -1) {
+                        teaserendindex = nextwordindex;
+                    }
+                    teaser = (teaserstartindex > 0) ? "..." : "";
+                    teaser += result.doc.body.substring(teaserstartindex, teaserendindex) + "...";
+                } else {
+                    teaser = result.doc.body.substr(0, 80) + "...";
+                }
+
+                display.append('<li><a href="' + result.ref + '">' + result.doc.title + '</a>: '
+                    + teaser + "</li>");
+            }
+
+            // Display and scroll to results
+            sidebar.scrollTop(0);
+            outer.slideDown();
+        } else {
+            // searchbar can shrink
+            $(e.target).removeClass("active");
+            outer.slideUp();
+            display.empty();
+        }
+    });
 
     // Theme button
     $("#theme-toggle").click(function(){
@@ -361,7 +442,7 @@ function run_rust_code(code_block) {
     }
 
     let text = playpen_text(code_block);
-    
+
     var params = {
 	channel: "stable",
 	mode: "debug",
@@ -392,3 +473,46 @@ function run_rust_code(code_block) {
         },
     });
 }
+
+function create_text_searchindex() {
+    var searchindex = elasticlunr(function () {
+        this.addField('body');
+        this.addField('title');
+        this.setRef('id');
+    });
+    var content = $("#content");
+    var paragraphs = content.children();
+    var curr_title = "";
+    var curr_body = "";
+    var curr_ref = "";
+    var push = function(ref) {
+        if ((curr_title.length > 0 || curr_body.length > 0) && curr_ref.length > 0) {
+            var doc = {
+                "id": curr_ref,
+                "body": curr_body,
+                "title": curr_title
+            }
+            searchindex.addDoc(doc);
+        }
+        curr_body = "";
+        curr_title = "";
+        curr_ref = "";
+    };
+    paragraphs.each(function(index, element) {
+        // todo uppercase
+        var el = $(element);
+        if (el.prop('nodeName').toUpperCase() == "A") {
+            // new header, push old paragraph to index
+            push(index);
+            curr_title = el.text();
+            curr_ref = el.attr('href');
+        } else {
+            curr_body += " \n " + el.text();
+        }
+        // last paragraph
+        if (index == paragraphs.length - 1) {
+            push(index);
+        }
+    });
+    return searchindex;
+}

src/theme/index.hbs

@@ -48,6 +48,14 @@
             }
         </script>
 
+        <!-- Fetch elasticlunr.js from CDN but have a local fallback -->
+        <script src="https://cdnjs.cloudflare.com/ajax/libs/elasticlunr/0.9.6/elasticlunr.min.js"></script>
+        <script>
+            if (typeof elasticlunr == 'undefined') {
+                document.write(unescape("%3Cscript src='elasticlunr.min.js'%3E%3C/script%3E"));
+            }
+        </script>
+
         <!-- Fetch store.js from local - TODO add CDN when 2.x.x is available on cdnjs -->
         <script src="store.js"></script>
 
@@ -68,6 +76,11 @@
         </script>
 
         <div id="sidebar" class="sidebar">
+            <div id="searchresults-outer" class="searchresults-outer">
+                <div class="searchresults-header" id="searchresults-header"></div>
+                <ul id="searchresults">
+                </ul>
+            </div>
             {{#toc}}{{/toc}}
         </div>
 
@@ -78,6 +91,8 @@
                     <div class="left-buttons">
                         <i id="sidebar-toggle" class="fa fa-bars" title="Toggle sidebar"></i>
                         <i id="theme-toggle" class="fa fa-paint-brush" title="Change theme"></i>
+                        <input type="search" id="searchbar" name="searchbar" placeholder="Search this book ...">
+                        <i id="search-go" class="fa fa-search" title="Search!"></i>
                     </div>
 
                     <h1 class="menu-title">{{ book_title }}</h1>
@@ -138,7 +153,7 @@
         <script>
             var localAddrs = ["localhost", "127.0.0.1", ""];
 
-            // make sure we don't activate google analytics if the developer is 
+            // make sure we don't activate google analytics if the developer is
             // inspecting the book locally...
             if (localAddrs.indexOf(document.location.hostname) === -1) {
                 (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){