Minor refactoring

src/controllers/sheetmanage.js

@@ -78,7 +78,7 @@ const sheetmanage = {
         let copyWord = "(" + locale_info.copy;
         const copy_i = name.toString().indexOf(copyWord);
 
-        if (copy_i > -1) {
+        if (~copy_i) {
             name = name.toString().substring(0, copy_i);
         }