diff --git a/tools/perf_view/ort_perf_view.html b/tools/perf_view/ort_perf_view.html
index 6142161861..fc8becd109 100644
--- a/tools/perf_view/ort_perf_view.html
+++ b/tools/perf_view/ort_perf_view.html
@@ -42,19 +42,20 @@
     <input id="file-selector" type="file" accept=".json" style="display:none"/>
     </div>
     <script>
+      'use strict';
       var raw_data_in_json = null;
-      
+
       const fileButton = document.getElementById('file-button');
       fileButton.addEventListener('click', (event) => {
         document.getElementById('file-selector').click();
       });
-      
+
       const fileSelector = document.getElementById('file-selector');
       fileSelector.addEventListener('change', (event) => {
         document.getElementById('file-label').style.display = 'none';
         document.getElementById('file-button').style.display = 'none';
         document.getElementById('file-selector').style.display = 'none';
-        preloader = anychart.ui.preloader();
+        var preloader = anychart.ui.preloader();
         preloader.render();
         preloader.visible(true);
 
@@ -63,8 +64,8 @@
         const reader = new FileReader();
         reader.addEventListener('load', (event) => {
           raw_data_in_json = JSON.parse(event.target.result);
-          summarized_cpu = JSON.parse("{}");
-          summarized_gpu = JSON.parse("{}");
+          var summarized_cpu = JSON.parse("{}");
+          var summarized_gpu = JSON.parse("{}");
           for (var i = 0; i < raw_data_in_json.length; i++) {
             var node = raw_data_in_json[i];
             if (node.cat == null ||node.name == null || node.args == null || node.args.op_name == null) continue;
@@ -130,7 +131,7 @@
           } else {
             document.getElementById("gpu").className = "no_view";
           }
-          
+
           preloader.visible(false);
         });
         reader.readAsText(fileList[0]);