buffer: fast-case for empty string in byteLength

When the string is empty, calling the binding is unnecessary and slow.

PR-URL: https://github.com/iojs/io.js/pull/1441
Reviewed-by: Jeremiah Senkpiel <fishrock123@rocketmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Christian Tellnes <christian@tellnes.no>

diff --git a/lib/buffer.js b/lib/buffer.js
index f125806..8f4e34d 100644 (file)
--- a/lib/buffer.js
+++ b/lib/buffer.js
@@ -276,6 +276,9 @@ function byteLength(string, encoding) {
   if (typeof(string) !== 'string')
     string = String(string);
 
+  if (string.length === 0)
+    return 0;
+
   switch (encoding) {
     case 'ascii':
     case 'binary':