rewrite to a module

extra_modules/xor.js

@@ -1,27 +1,19 @@
 function XOR_hex(a, b) {
-    var res = "",
-        i = a.length,
-        j = b.length;
-    while (i-->0 && j-->0)
+    var res = "", i = a.length, j = b.length;
+    while (i-- > 0 && j-- > 0)
         res = (parseInt(a.charAt(i), 16) ^ parseInt(b.charAt(j), 16)).toString(16) + res;
     return res;
 }
-
-function hexEncode(a){
+function hexEncode(a) {
     let hex;
-
     let result = "";
-    for (let i=0; i<a.length; i++) {
+    for (let i = 0; i < a.length; i++) {
         hex = a.charCodeAt(i).toString(16);
-        result += ("000"+hex).slice(-4);
+        result += ("000" + hex).slice(-4);
     }
-
-    return result
+    return result;
 }
-
-function xor(a,b) {
-    return XOR_hex(hexEncode(a),hexEncode(b)).toString("hex")
+function xor(a, b) {
+    return XOR_hex(hexEncode(a), hexEncode(b)).toString("hex");
 }
-
-module.exports = xor
-  
+export default xor;