Add scrollToItem method

bower.json

@@ -7,7 +7,7 @@
     "list",
     "virtual-list"
   ],
-  "version": "1.3.2",
+  "version": "1.3.3",
   "homepage": "https://github.com/PolymerElements/iron-list",
   "authors": [
     "The Polymer Authors"

iron-list.html

@@ -1033,12 +1033,14 @@
       if (!el || el._templateInstance.__key__ !== key) {
         return;
       }
+
       if (dot >= 0) {
         path = this.as + '.' + path.substring(dot+1);
         el._templateInstance.notifyPath(path, value, true);
       } else {
         el._templateInstance[this.as] = value;
       }
+
     },
 
     /**
@@ -1340,15 +1342,27 @@
         this._scrollHeight = this._estScrollHeight;
       }
     },
+
     /**
      * Scroll to a specific item in the virtual list regardless
      * of the physical items in the DOM tree.
      *
+     * @method scrollToItem
+     * @param {(Object)} item The item to be scrolled to
+     */
+    scrollToItem: function(item){
+      return this.scrollToIndex(this.items.indexOf(item));
+    },
+
+    /**
+     * Scroll to a specific index in the virtual list regardless
+     * of the physical items in the DOM tree.
+     *
      * @method scrollToIndex
      * @param {number} idx The index of the item
      */
     scrollToIndex: function(idx) {
-      if (typeof idx !== 'number') {
+      if (typeof idx !== 'number' || idx < 0 || idx > this.items.length - 1) {
         return;
       }
 

test/basic.html

@@ -150,6 +150,35 @@
       }, 100);
     });
 
+    test('scroll to item', function(done) {
+      list.items = buildDataSet(100);
+
+      setTimeout(function() {
+        list.scrollToItem(list.items[30]);
+        assert.equal(list.firstVisibleIndex, 30);
+
+        list.scrollToItem(list.items[0]);
+        assert.equal(list.firstVisibleIndex, 0);
+
+        var rowHeight = getFirstItemFromList(list).offsetHeight;
+        var viewportHeight = list.offsetHeight;
+        var itemsPerViewport = Math.floor(viewportHeight/rowHeight);
+
+        list.scrollToItem(list.items[99]);
+        assert.equal(list.firstVisibleIndex, list.items.length - itemsPerViewport);
+
+        // make the height of the viewport same as the height of the row
+        // and scroll to the last item
+        list.style.height = list._physicalItems[0].offsetHeight + 'px';
+
+        setTimeout(function() {
+          list.scrollToItem(list.items[99]);
+          assert.equal(list.firstVisibleIndex, 99);
+          done();
+        }, 100);
+      }, 100);
+    });
+
     test('scroll to top', function(done) {
       list.items = buildDataSet(100);
       Polymer.dom.flush();