From 16ea356ad0c3b4bbb5d3df8c4559550c5d2eda47 Mon Sep 17 00:00:00 2001
From: Jackson Tian <puling.tyq@alibaba-inc.com>
Date: Thu, 16 Apr 2015 23:31:34 +0800
Subject: [PATCH] buffer: improve Buffer.byteLength(string, encoding)

When string is empty, it will running into binding also.
It make the performance is wasted.
---
 lib/buffer.js | 32 ++++++++++++++++++--------------
 1 file changed, 18 insertions(+), 14 deletions(-)

diff --git a/lib/buffer.js b/lib/buffer.js
index f125806622d49d..86f66834f39f3f 100644
--- a/lib/buffer.js
+++ b/lib/buffer.js
@@ -276,23 +276,27 @@ function byteLength(string, encoding) {
   if (typeof(string) !== 'string')
     string = String(string);
 
-  switch (encoding) {
-    case 'ascii':
-    case 'binary':
-    case 'raw':
-      return string.length;
+  if (string.length > 0) {
+    switch (encoding) {
+      case 'ascii':
+      case 'binary':
+      case 'raw':
+        return string.length;
 
-    case 'ucs2':
-    case 'ucs-2':
-    case 'utf16le':
-    case 'utf-16le':
-      return string.length * 2;
+      case 'ucs2':
+      case 'ucs-2':
+      case 'utf16le':
+      case 'utf-16le':
+        return string.length * 2;
 
-    case 'hex':
-      return string.length >>> 1;
-  }
+      case 'hex':
+        return string.length >>> 1;
+    }
 
-  return binding.byteLength(string, encoding);
+    return binding.byteLength(string, encoding);
+  } else {
+    return 0;
+  }
 }
 
 Buffer.byteLength = byteLength;