diff --git a/src/js/api.js b/src/js/api.js
index 8edef4c..e6a5820 100644
--- a/src/js/api.js
+++ b/src/js/api.js
@@ -24,7 +24,7 @@ const SendXMLHttpRequest = (url, data, success, error, fail) => {
     };
 
     xhr.open(data !== null ? 'POST' : 'GET', url, true);
-    xhr.setRequestHeader("Content-type", "application/json; charset=UTF-8");
+    xhr.setRequestHeader('Content-type', 'application/json; charset=UTF-8');
     xhr.send(data !== null ? JSON.stringify(data) : null);
 };
 
diff --git a/src/js/comment.js b/src/js/comment.js
index 4b2f0f2..73cbb05 100644
--- a/src/js/comment.js
+++ b/src/js/comment.js
@@ -13,9 +13,9 @@ class Comment {
         });
 
         this.player.template.commentColorSettingBox.addEventListener('click', () => {
-            const sele = this.player.template.commentColorSettingBox.querySelector(`input:checked+span`);
+            const sele = this.player.template.commentColorSettingBox.querySelector('input:checked+span');
             if (sele) {
-                const color = this.player.template.commentColorSettingBox.querySelector(`input:checked`).value;
+                const color = this.player.template.commentColorSettingBox.querySelector('input:checked').value;
                 this.player.template.commentSettingFill.style.fill = color;
                 this.player.template.commentInput.style.color = color;
                 this.player.template.commentSendFill.style.fill = color;
diff --git a/src/js/danmaku.js b/src/js/danmaku.js
index 7a67b19..88382b2 100644
--- a/src/js/danmaku.js
+++ b/src/js/danmaku.js
@@ -214,8 +214,8 @@ class Danmaku {
                 if (!dan[i].color) {
                     dan[i].color = '#fff';
                 }
-                const item = document.createElement(`div`);
-                item.classList.add(`dplayer-danmaku-item`);
+                const item = document.createElement('div');
+                item.classList.add('dplayer-danmaku-item');
                 item.classList.add(`dplayer-danmaku-${dan[i].type}`);
                 if (dan[i].border) {
                     item.innerHTML = `<span style="border:${dan[i].border}">${dan[i].text}</span>`;
@@ -260,7 +260,7 @@ class Danmaku {
 
                 if (tunnel >= 0) {
                     // move
-                    item.classList.add(`dplayer-danmaku-move`);
+                    item.classList.add('dplayer-danmaku-move');
 
                     // insert
                     docFragment.appendChild(item);
@@ -315,12 +315,12 @@ class Danmaku {
 
     htmlEncode (str) {
         return str.
-            replace(/&/g, "&amp;").
-            replace(/</g, "&lt;").
-            replace(/>/g, "&gt;").
-            replace(/"/g, "&quot;").
-            replace(/'/g, "&#x27;").
-            replace(/\//g, "&#x2f;");
+            replace(/&/g, '&amp;').
+            replace(/</g, '&lt;').
+            replace(/>/g, '&gt;').
+            replace(/"/g, '&quot;').
+            replace(/'/g, '&#x27;').
+            replace(/\//g, '&#x2f;');
     }
 
     resize () {
diff --git a/src/js/i18n.js b/src/js/i18n.js
index 99611a5..9dc0065 100644
--- a/src/js/i18n.js
+++ b/src/js/i18n.js
@@ -21,7 +21,7 @@ function i18n (lang) {
 
 // add translation text here
 const tranTxt = {
-    "zh-cn" : {
+    'zh-cn' : {
         'Danmaku is loading': '弹幕加载中',
         'Top': '顶部',
         'Bottom': '底部',
@@ -58,7 +58,7 @@ const tranTxt = {
         'Live': '直播',
         'Video info': '视频统计信息',
     },
-    "zh-tw" : {
+    'zh-tw' : {
         'Danmaku is loading': '彈幕加載中',
         'Top': '頂部',
         'Bottom': '底部',