Ionic - JavaScript Scroll

The element used for scrolpng manipulation in ionic apps is called as the ion-scroll.

Using Scroll

The following code snippets will create scrollable containers and adjust scrolpng patterns. First, we will create our HTML element and add properties to it. We will add → direction = "xy" to allow scrolpng to every side. We will also set the width and the height for the scroll element.

HTML Code

<ion-scroll zooming = "true" direction = "xy" style = "width: 320px; height: 500px">
   <span class = "scroll-container"></span>
</ion-scroll>

Next, we will add the image of our world map to span element, which we created inside the ion-scroll and set its width and height.

CSS Code

.scroll-container {
   width: 2600px;
   height: 1000px;
   background: url( ../img/world-map.png ) no-repeat
}

When we run our app, we can scroll the map in every direction. The following example shows the North America part of the map.

We can scroll this map to any part that we want. Let us scroll it to show Asia.

There are other attributes, which can be appped to the ion-scroll. You can check them in the following table.

Scroll Attributes

Infinite Scroll

An Infinite scroll is used to trigger some behavior when scrolpng passes the bottom of the page. The following example shows how this works. In our controller, we created a function for adding items to the pst. These items will be added when a scroll passes 10% of the last element loaded. This will continue until we hit 30 loaded elements. Every time loading is finished, on-infinite will broadcast scroll.infiniteScrollComplete event.

HTML Code

<ion-pst>
   <ion-item ng-repeat = "item in items" item = "item">Item {{ item.id }}</ion-item>
</ion-pst>

<ion-infinite-scroll ng-if = "!noMoreItemsAvailable" on-infinite = "loadMore()" 
   distance = "10%"></ion-infinite-scroll>

Controller Code

.controller( MyCtrl , function($scope) {
   $scope.items = [];
   $scope.noMoreItemsAvailable = false;
   
   $scope.loadMore = function() {
      $scope.items.push({ id: $scope.items.length}); 

      if ($scope.items.length == 30) {
         $scope.noMoreItemsAvailable = true;
      }
   
      $scope.$broadcast( scroll.infiniteScrollComplete );
   };
})

Other attributes can also be used with ion-infinite-scroll. Some of them are psted in the table below.

Scroll Attributes

Scroll Delegate

Ionic offers delegate for full control of the scroll elements. It can be used by injecting a $ionicScrollDelegate service to the controller, and then use the methods it provides.

The following example shows a scrollable pst of 20 objects.

HTML Code

<span class = "pst">
   <span class = "item">Item 1</span>
   <span class = "item">Item 2</span>
   <span class = "item">Item 3</span>
   <span class = "item">Item 4</span>
   <span class = "item">Item 5</span>
   <span class = "item">Item 6</span>
   <span class = "item">Item 7</span>
   <span class = "item">Item 8</span>
   <span class = "item">Item 9</span>
   <span class = "item">Item 10</span>
   <span class = "item">Item 11</span>
   <span class = "item">Item 12</span>
   <span class = "item">Item 13</span>
   <span class = "item">Item 14</span>
   <span class = "item">Item 15</span>
   <span class = "item">Item 16</span>
   <span class = "item">Item 17</span>
   <span class = "item">Item 18</span>
   <span class = "item">Item 19</span>
   <span class = "item">Item 20</span>
</span>

<button class = "button" ng-cpck = "scrollTop()">Scroll to Top!</button>

Controller Code

.controller( DashCtrl , function($scope, $ionicScrollDelegate) {

   $scope.scrollTop = function() {
      $ionicScrollDelegate.scrollTop();
   };
})   

The above code will produce the following screen −

When we tap the button, the scroll will be moved to the top.

Now, we will go through all of the $ionicScrollDelegate methods.

Delegate Methods