optimized createFromHexString

Author: christkv

lib/bson/objectid.js

@@ -285,22 +285,19 @@ var convertToHex = function(bytes) {
 */
 ObjectID.createFromHexString = function createFromHexString (string) {
   // Throw an error if it's not a valid setup
-  if(typeof string === 'undefined' || string != null && string.length != 24)
+  if(typeof string === 'undefined' || string != null && string.length != 24) {
     throw new Error("Argument passed in must be a single String of 12 bytes or a string of 24 hex characters");
-
-  var length = string.length;
-
-  if(length > 12*2) {
-    throw new Error('Id cannot be longer than 12 bytes');
   }
 
+  // Use Buffer.from method if available
+  if(hasBufferType) return new ObjectID(Buffer.from(string, 'hex'));
+
   // Calculate lengths
-  var sizeof = length >> 1;
-  var array = new _Buffer(sizeof);
+  var array = new _Buffer(12);
   var n = 0;
   var i = 0;
 
-  while (i < length) {
+  while (i < 24) {
     array[n++] = decodeLookup[string.charCodeAt(i++)] << 4 | decodeLookup[string.charCodeAt(i++)]
   }