From f9fbc3aeabff2a7ab2cc1b932f1ee82cdde643d6 Mon Sep 17 00:00:00 2001
From: Anatoli Papirovski <apapirovski@mac.com>
Date: Mon, 4 Sep 2017 08:53:43 -0400
Subject: [PATCH] buffer: improve Buffer.from performance

Using == null in code paths that are expected to mostly receive
objects, arrays or other more complex data types is not
ideal because typecasting these types is very slow. Change
to instead check === null || === undefined. Also move one
variable assignment in fromString after an if condition
that doesn't need it (and returns if truthy).

Refs: https://jsperf.com/triple-equals-vs-double-equals/3
---
 lib/buffer.js | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/lib/buffer.js b/lib/buffer.js
index ae9ec5fc8eaad1..7a44ca0f260539 100644
--- a/lib/buffer.js
+++ b/lib/buffer.js
@@ -193,7 +193,7 @@ Buffer.from = function from(value, encodingOrOffset, length) {
   if (isAnyArrayBuffer(value))
     return fromArrayBuffer(value, encodingOrOffset, length);
 
-  if (value == null) {
+  if (value === null || value === undefined) {
     throw new errors.TypeError(
       'ERR_INVALID_ARG_TYPE',
       'first argument',
@@ -208,7 +208,7 @@ Buffer.from = function from(value, encodingOrOffset, length) {
     );
 
   const valueOf = value.valueOf && value.valueOf();
-  if (valueOf != null && valueOf !== value)
+  if (valueOf !== null && valueOf !== undefined && valueOf !== value)
     return Buffer.from(valueOf, encodingOrOffset, length);
 
   var b = fromObject(value);
@@ -322,9 +322,9 @@ function allocate(size) {
 function fromString(string, encoding) {
   var length;
   if (typeof encoding !== 'string' || encoding.length === 0) {
-    encoding = 'utf8';
     if (string.length === 0)
       return new FastBuffer();
+    encoding = 'utf8';
     length = byteLengthUtf8(string);
   } else {
     length = byteLength(string, encoding, true);