add scroll into view implementation

src/utils/scroll-into-view.js

@@ -0,0 +1,21 @@
+import Vue from 'vue';
+
+export default function scrollIntoView(container, selected) {
+  if (Vue.prototype.$isServer) return;
+
+  if (!selected) {
+    container.scrollTop = 0;
+    return;
+  }
+
+  const top = selected.offsetTop;
+  const bottom = selected.offsetTop + selected.offsetHeight;
+  const viewRectTop = container.scrollTop;
+  const viewRectBottom = viewRectTop + container.clientHeight;
+
+  if (top < viewRectTop) {
+    container.scrollTop = top;
+  } else if (bottom > viewRectBottom) {
+    container.scrollTop = bottom - container.clientHeight;
+  }
+}