diff --git a/script/gallery.ts b/script/gallery.ts
index 1671a9d..6fd4f2d 100644
--- a/script/gallery.ts
+++ b/script/gallery.ts
@@ -146,10 +146,9 @@ function sortFilters(cmp: (a: Node, b: Node) => number) {
 }
 
 function sortFiltersAlpha(e: Event) {
-  function getName(node: Node) {
-    if (node.nodeType == Node.ELEMENT_NODE) {
-      let elt = node as Element;
-      return elt.getElementsByTagName('input')[0].value;
+  function getName(node: Node): string {
+    if (node instanceof Element) {
+      return node.getElementsByTagName('input')[0].value;
     } else {
       return '';
     }
@@ -160,9 +159,8 @@ function sortFiltersAlpha(e: Event) {
 
 function sortFiltersUses(e: Event) {
   function getUses(node: Node) {
-    if (node.nodeType == Node.ELEMENT_NODE) {
-      let elt = node as Element;
-      let countStr = elt.getElementsByTagName('label')[0].dataset.count;
+    if (node instanceof Element) {
+      const countStr = node.getElementsByTagName('label')[0].dataset.count;
       return countStr ? +countStr : 0;
     } else {
       return 0;