From 5adcdd1296c33a173e47ebe51ac21f60923d5fbe Mon Sep 17 00:00:00 2001
From: Divpreet <divpreet.singh@gmail.com>
Date: Thu, 24 Dec 2015 17:18:30 +1100
Subject: [PATCH] Performance improvement for very long list scenarios.

Creating a separate complete list of all elements which can be displayed
without running a matcher on empty string when the dropdown is to be
pulled down.
Also, backspace and delete button press will trigger any change only if
the string is non empty to ignore unnecessary trigger of functions
---
 js/bootstrap-combobox.js | 23 ++++++++++++++++++++---
 1 file changed, 20 insertions(+), 3 deletions(-)

diff --git a/js/bootstrap-combobox.js b/js/bootstrap-combobox.js
index 1639986..5c607c6 100755
--- a/js/bootstrap-combobox.js
+++ b/js/bootstrap-combobox.js
@@ -254,7 +254,8 @@
           this.hide();
         } else {
           this.clearElement();
-          this.lookup();
+          this.$menu.html(this.sourceElements);
+          this.show();
         }
       }
     }
@@ -282,6 +283,13 @@
 
   , refresh: function () {
     this.source = this.parse();
+    var that = this;
+    this.sourceElements = $(this.source).map(function (i, item) {
+      i = $(that.options.item).attr('data-value', item);
+      i.find('a').html(item);
+      return i[0];
+    })
+    this.$menu.html(this.sourceElements);
     this.options.items = this.source.length;
   }
 
@@ -371,8 +379,17 @@
           if (!this.shown) {return;}
           this.hide();
           break;
-
-        default:
+        
+		case 8:  //backspace
+        case 46: //delete
+          if(!this.$element.val()){
+            this.clearTarget();
+            this.triggerChange();
+            this.clearElement();
+            break;
+          }
+        
+		default:
           this.clearTarget();
           this.lookup();
       }