🐛 [bug]fix android4.4 TouchEvent has PageY propery (#9)

Author: lanjingling0510

lib/DatePickerItem.js

@@ -170,13 +170,19 @@ class DatePickerItem extends Component {
     }
 
     handleStart(event) {
-        this.touchY = event.pageY || event.targetTouches[0].pageY;
+        this.touchY =
+            (event.targetTouches && event.targetTouches[0] && event.targetTouches[0].pageY) ||
+            event.pageY;
+
         this.translateY = this.state.translateY;
     }
 
 
     handleMove(event) {
-        const touchY = event.pageY || event.targetTouches[0].pageY;
+        const touchY =
+            (event.targetTouches && event.targetTouches[0] && event.targetTouches[0].pageY) ||
+            event.pageY;
+
         const dir = touchY - this.touchY;
         const translateY = this.translateY + dir;
         const direction = dir > 0 ? -1 : 1;