angular-ui · dhilt · Aug 3, 2019 · Jul 16, 2019 · Jul 31, 2019 · Jul 31, 2019
diff --git a/README.md b/README.md
@@ -249,6 +249,8 @@ Adapter object implements the following properties:
 * `topVisible`/`bottomVisible` - a read only reference to the item currently in the topmost/bottommost visible position.
 * `topVisibleElement`/`bottomVisibleElement` - a read only reference to the DOM element currently in the topmost/bottommost visible position.
 * `topVisibleScope`/`bottomVisibleScope` - a read only reference to the scope created for the item currently in the topmost/bottommost visible position.
+* `bufferLength` - a number of items currently in the ui-scroll buffer; equal to a number of DOM elements that are present in visible and invisible parts of the ui-scroll viewport.
+* `bufferFirst`/`bufferLast` - a read only reference to the first/last item currently in the ui-scroll buffer.
 * `disabled` - setting `disabled` to `true` disables scroller's scroll/resize events handlers. This can be useful if you have multiple scrollers within the same scrollViewport and you want to prevent some of them from responding to the events.
 
 Adapter object implements the following methods
@@ -475,6 +477,10 @@ Pull Rerquest should include source code (./scr) changes, may include tests (./t
 
 ## Change log
 
+### v1.7.5
+ * Added bufferFirst, bufferLast, bufferLength read-only properties to the Adapter.
+ * Fixed reload unsubscribe issue [226](https://github.com/angular-ui/ui-scroll/issues/226).
+
 ### v1.7.4
  * Fixed jqLite/jQuery confrontation.
 

diff --git a/bower.json b/bower.json
@@ -1,7 +1,7 @@
 {
   "name": "angular-ui-scroll",
   "description": "AngularJS infinite scrolling module",
-  "version": "1.7.4",
+  "version": "1.7.5",
   "main": "./dist/ui-scroll.js",
   "homepage": "https://github.com/angular-ui/ui-scroll.git",
   "license": "MIT",

diff --git a/demo/bufferItems/bufferItems.html b/demo/bufferItems/bufferItems.html
@@ -0,0 +1,52 @@
+<!doctype html>
+<html>
+
+<head>
+  <meta charset="utf-8">
+  <title>Buffer first, last, length</title>
+  <script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.7.1/angular.js"></script>
+  <script src="../../dist/ui-scroll.js"></script>
+  <script src="bufferItems.js"></script>
+  <link rel="stylesheet" href="../css/style.css" type="text/css" />
+</head>
+
+<body ng-app="application" ng-controller="mainController">
+
+  <div class="cont cont-global">
+
+    <a class="back" href="../index.html">browse other examples</a>
+
+    <h1 class="page-header page-header-exapmle">Buffer first, last, length</h1>
+
+    <div class="description">
+      The ui-scroll Adapter has 3 read-only properties which provide information of current ui-scroll Buffer state.
+      The buffer contains some visible items and some items that are out of visible part of the viewport.
+      So with these properties we can get the topmost and the bottommost items that the ui-scroll is dealing with at the moment.
+      At the template's layer it may look like
+
+      <div class="code">
+        <pre>{{adapter.bufferFirst}<!---->}
+{{adapter.bufferLast}<!---->}
+{{adapter.bufferLength}<!---->}
+
+&lt;li ui-scroll="item in datasource" adapter="adapter"&gt;{{item}<!---->}&lt;/li&gt;</pre>
+      </div>
+    </div>
+
+    <div class="info">
+      <div class="info-item"><span class="info-item-label">First buffer</span> {{adapter.bufferFirst}}</div>
+      <div class="info-item"><span class="info-item-label">Last buffer</span> {{adapter.bufferLast}}</div>
+      <div class="info-item"><span class="info-item-label">Buffer length:</span> {{adapter.bufferLength}}</div>
+    </div>
+
+    <div class="viewport" id="viewport-listScroller" ui-scroll-viewport>
+      <ul>
+        <li ui-scroll="item in datasource" adapter="adapter">{{item}}</li>
+      </ul>
+    </div>
+
+  </div>
+
+</body>
+
+</html>
diff --git a/demo/bufferItems/bufferItems.js b/demo/bufferItems/bufferItems.js
@@ -0,0 +1,20 @@
+angular.module('application', ['ui.scroll'])
+  .controller('mainController', [
+    '$scope', '$log', '$timeout', function ($scope, console, $timeout) {
+
+      $scope.adapter = {};
+
+      $scope.datasource = {};
+
+      $scope.datasource.get = function (index, count, success) {
+        $timeout(function () {
+          var result = [];
+          for (var i = index; i <= index + count - 1; i++) {
+            result.push("item #" + i);
+          }
+          success(result);
+        }, 0);
+      };
+
+    }
+  ]);
diff --git a/demo/index.html b/demo/index.html
@@ -64,6 +64,11 @@ <h1 class="page-header">Scroller Examples</h1>
         Bottom visible (Adapter)
       </a>
     </li>
+    <li>
+      <a href="bufferItems/bufferItems.html">
+        Buffer first, last, length
+      </a>
+    </li>
     <li>
       <a href="reload100/reload100.html">
         Reload datasource to specified index

diff --git a/dist/ui-scroll-grid.js b/dist/ui-scroll-grid.js
diff --git a/dist/ui-scroll.js b/dist/ui-scroll.js
diff --git a/dist/ui-scroll.js.map b/dist/ui-scroll.js.map
diff --git a/dist/ui-scroll.min.js b/dist/ui-scroll.min.js
diff --git a/dist/ui-scroll.min.js.map b/dist/ui-scroll.min.js.map
diff --git a/package.json b/package.json
@@ -1,7 +1,7 @@
 {
   "name": "angular-ui-scroll",
   "description": "AngularJS infinite scrolling module",
-  "version": "1.7.4",
+  "version": "1.7.5",
   "src": "./src/",
   "public": "./dist/",
   "main": "./dist/ui-scroll.js",

diff --git a/src/modules/adapter.js b/src/modules/adapter.js
@@ -64,6 +64,14 @@ class Adapter {
       });
     }
 
+    // read-only immediately calculated public properties
+    const publicPropsImmediate = ['bufferFirst', 'bufferLast', 'bufferLength'];
+    for (let i = publicPropsImmediate.length - 1; i >= 0; i--) {
+      Object.defineProperty(this.publicContext, publicPropsImmediate[i], {
+        get: () => this[publicPropsImmediate[i]]
+      });
+    }
+
     // non-read-only public property
     Object.defineProperty(this.publicContext, 'disabled', {
       get: () => this.disabled,
@@ -87,6 +95,18 @@ class Adapter {
     return !this.buffer.length;
   }
 
+  get bufferLength() {
+    return this.buffer.getItems().length;
+  }
+
+  get bufferFirst() {
+    return this.buffer.getFirstItem();
+  }
+
+  get bufferLast() {
+    return this.buffer.getLastItem();
+  }
+
   append(newItems) {
     this.buffer.append(newItems);
     this.doAdjust();

diff --git a/src/modules/buffer.js b/src/modules/buffer.js
@@ -144,6 +144,26 @@ export default function ScrollBuffer(elementRoutines, bufferSize, startIndex) {
         }
       });
       return Math.max(0, bottom - top);
+    },
+
+    getItems() {
+      return buffer.filter(item => item.op === 'none');
+    },
+
+    getFirstItem() {
+      const list = buffer.getItems();
+      if (!list.length) {
+        return null;
+      }
+      return list[0].item;
+    },
+
+    getLastItem() {
+      const list = buffer.getItems();
+      if (!list.length) {
+        return null;
+      }
+      return list[list.length - 1].item;
     }
 
   });

diff --git a/test/AdapterTestsSpec.js b/test/AdapterTestsSpec.js
@@ -1300,4 +1300,32 @@ describe('uiScroll', function () {
 
   });
 
+  describe('adapter bufferFirst, bufferLast, bufferLength', function () {
+    var scrollSettings = { datasource: 'myMultipageDatasource', adapter: 'adapter', viewportHeight: 80, itemHeight: 20 };
+
+    it('without scroll', function () {
+      runTest(scrollSettings,
+        function (viewport, scope) {
+          expect(scope.adapter.bufferFirst).toBe('item1');
+          expect(scope.adapter.bufferLast).toBe('item10');
+          expect(scope.adapter.bufferLength).toBe(10);
+        }
+      );
+    });
+
+    it('scroll to the bottom', function () {
+      runTest(scrollSettings,
+        function (viewport, scope) {          
+          viewport.scrollTop(10000);
+          viewport.trigger('scroll');
+
+          expect(scope.adapter.bufferFirst).toBe('item5');
+          expect(scope.adapter.bufferLast).toBe('item20');
+          expect(scope.adapter.bufferLength).toBe(16);
+        }
+      );
+    });
+
+  });
+
 });