remove alert

js/chess.js

@@ -21,7 +21,7 @@ var curCol = 0, myCol = 2, cur, messages = [0, 0, 0];
 
 function isMobile() {
     let flag = /Android|webOS|iPhone|iPad|iPod|BlackBerry|IEMobile|Opera Mini/i.test(navigator.userAgent);
-    alert(navigator.userAgent + '\n' + flag)
+    // alert(navigator.userAgent + '\n' + flag)
     return flag;
 }