fix($animate): insert elements at the start of the parent container instead of at the end

With 1.2.x, $animate.enter and $animate.move both insert the element at the end of the provided
parent container element when only the parent element is provided. If an after element is provided
then they will place the inserted element after that one. This works fine, but there is no way to
place an item at the top of the provided parent container using both these functions.

Closes angular#4934
Closes angular#6275

BREAKING CHANGE: $animate will no longer default the after parameter to the last element of the parent
container. Instead, when after is not specified, the new element will be inserted as the first child of
the parent container.

To update existing code change any instances of $animate.enter() or $animate.move() from:

$animate.enter(element, parent);

to:

$animate.enter(element, parent, angular.element(parent[0].lastChild));

Author: matsko

src/ng/animate.js

@@ -111,8 +111,9 @@ var $AnimateProvider = ['$provide', function($provide) {
        * @ngdoc method
        * @name $animate#enter
        * @function
-       * @description Inserts the element into the DOM either after the `after` element or within
-       *   the `parent` element. Once complete, the done() callback will be fired (if provided).
+       * @description Inserts the element into the DOM either after the `after` element or
+       * as the first child within the `parent` element. Once complete, the done() callback
+       * will be fired (if provided).
        * @param {DOMElement} element the element which will be inserted into the DOM
        * @param {DOMElement} parent the parent element which will append the element as
        *   a child (if the after element is not present)
@@ -122,14 +123,9 @@ var $AnimateProvider = ['$provide', function($provide) {
        *   inserted into the DOM
        */
       enter : function(element, parent, after, done) {
-        if (after) {
-          after.after(element);
-        } else {
-          if (!parent || !parent[0]) {
-            parent = after.parent();
-          }
-          parent.append(element);
-        }
+        after
+            ? after.after(element)
+            : parent.prepend(element);
         async(done);
       },
 

test/ng/animateSpec.js

@@ -15,6 +15,19 @@ describe("$animate", function() {
       expect(element.contents().length).toBe(1);
     }));
 
+    it("should enter the element to the start of the parent container",
+      inject(function($animate, $compile, $rootScope) {
+
+      for(var i = 0; i < 5; i++) {
+        element.append(jqLite('<div> ' + i + '</div>'));
+      }
+
+      var child = jqLite('<div>first</div>');
+      $animate.enter(child, element);
+
+      expect(element.text()).toEqual('first 0 1 2 3 4');
+    }));
+
     it("should remove the element at the end of leave animation", inject(function($animate, $compile, $rootScope) {
       var child = $compile('<div></div>')($rootScope);
       element.append(child);