Optimize and fix sorting in bencode_dictionary.

lib/util/bencode.js

@@ -57,33 +57,21 @@ var bencode_list = function(list) {
 };
 
 var bencode_dictionary = function(dictionary) {
-  var key, value, temp;
-  var encoded = [];
+  var keys, key, i, len;
+  var encoded = '';
 
-  encoded.push('d');
-  for (key in dictionary) {
-    if (dictionary.hasOwnProperty(key)) {
-      value = dictionary[key];
+  keys = Object.keys(dictionary);
+  keys.sort();
 
-      encoded.push(sprintf('%s%s', bencode_string(key), bencode(value)));
-    }
+  encoded += 'd';
+  for (i = 0, len = keys.length; i < len; i++) {
+    key = keys[i];
+    value = dictionary[key];
+    encoded += bencode_string(key) + bencode(value);
   }
 
-  // Sort the dictionary items by the key name in alphabetic order
-  temp = encoded.splice(1);
-  temp.sort(function(a, b) {
-    var key_a, key_b;
-
-    key_a  = a.substr(a.indexOf(':') + 1);
-    key_b  = b.substr(b.indexOf(':') + 1);
-
-    return key_a.localeCompare(key_b);
-  });
-
-  encoded = encoded.concat(temp);
-  encoded.push('e');
-
-  return encoded.join('');
+  encoded += 'e';
+  return encoded;
 };
 
 /**