diff --git a/app/static/js/word_operation.js b/app/static/js/word_operation.js
index 3f83b07..39e8e72 100644
--- a/app/static/js/word_operation.js
+++ b/app/static/js/word_operation.js
@@ -1,12 +1,12 @@
 function familiar(index) {
-    var username = $("#username").text();
-    var word = $("#word_" + index).text();
-    var freq = $("#freq_" + index).text();
+    let username = $("#username").text();
+    let word = $("#word_" + index).text();
+    let freq = $("#freq_" + index).text();
     $.ajax({
         type:"get",
         url:"/" + username + "/" + word + "/familiar",
         success:function(resp){
-            var new_freq = freq - 1;
+            let new_freq = freq - 1;
             if(new_freq <1) {
                 $("#p_" + index).remove();
             } else {
@@ -17,22 +17,22 @@ function familiar(index) {
 }
 
 function unfamiliar(index) {
-    var username = $("#username").text();
-    var word = $("#word_" + index).text();
-    var freq = $("#freq_" + index).text();
+    let username = $("#username").text();
+    let word = $("#word_" + index).text();
+    let freq = $("#freq_" + index).text();
     $.ajax({
         type:"get",
         url:"/" + username + "/" + word + "/unfamiliar",
         success:function(resp){
-            var new_freq = parseInt(freq) + 1;
+            let new_freq = parseInt(freq) + 1;
             $("#freq_" + index).text(new_freq);
         }
     });
 }
 
 function del_word(index) {
-    var username = $("#username").text();
-    var word = $("#word_" + index).text();
+    let username = $("#username").text();
+    let word = $("#word_" + index).text();
     $.ajax({
         type:"get",
         url:"/" + username + "/" + word + "/del",
@@ -40,4 +40,4 @@ function del_word(index) {
             $("#p_" + index).remove();
         }
     });
-}
\ No newline at end of file
+}