merge: cache repeated function calls (TheAlgorithms#962)

Author: fahimfaisaal

Ciphers/Atbash.js

@@ -11,11 +11,13 @@ const Atbash = (str) => {
   }
 
   return str.replace(/[a-z]/gi, (char) => {
+    const charCode = char.charCodeAt()
+
     if (/[A-Z]/.test(char)) {
-      return String.fromCharCode(90 + 65 - char.charCodeAt())
+      return String.fromCharCode(90 + 65 - charCode)
     }
 
-    return String.fromCharCode(122 + 97 - char.charCodeAt())
+    return String.fromCharCode(122 + 97 - charCode)
   })
 }