Add configurable keypress delay before initiating search (#764)

source/javascripts/app/_search.js

@@ -6,6 +6,8 @@
 
   var content, searchResults;
   var highlightOpts = { element: 'span', className: 'search-highlight' };
+  var searchDelay = 0;
+  var timeoutHandle = 0;
 
   var index = new lunr.Index();
 
@@ -27,24 +29,44 @@
         body: body.text()
       });
     });
+
+    determineSearchDelay();
+  }
+  function determineSearchDelay() {
+    if(index.tokenStore.length>5000) {
+      searchDelay = 300;
+    }
   }
 
   function bind() {
     content = $('.content');
     searchResults = $('.search-results');
 
-    $('#input-search').on('keyup', search);
+    $('#input-search').on('keyup',function(e) {
+      var wait = function() {
+        return function(executingFunction, waitTime){
+          clearTimeout(timeoutHandle);
+          timeoutHandle = setTimeout(executingFunction, waitTime);
+        };
+      }();
+      wait(function(){
+        search(e);
+      }, searchDelay );
+    });
   }
 
   function search(event) {
+
+    var searchInput = $('#input-search')[0];
+
     unhighlight();
     searchResults.addClass('visible');
 
     // ESC clears the field
-    if (event.keyCode === 27) this.value = '';
+    if (event.keyCode === 27) searchInput.value = '';
 
-    if (this.value) {
-      var results = index.search(this.value).filter(function(r) {
+    if (searchInput.value) {
+      var results = index.search(searchInput.value).filter(function(r) {
         return r.score > 0.0001;
       });
 
@@ -54,10 +76,10 @@
           var elem = document.getElementById(result.ref);
           searchResults.append("<li><a href='#" + result.ref + "'>" + $(elem).text() + "</a></li>");
         });
-        highlight.call(this);
+        highlight.call(searchInput);
       } else {
         searchResults.html('<li></li>');
-        $('.search-results li').text('No Results Found for "' + this.value + '"');
+        $('.search-results li').text('No Results Found for "' + searchInput.value + '"');
       }
     } else {
       unhighlight();
@@ -73,3 +95,4 @@
     content.unhighlight(highlightOpts);
   }
 })();
+