From 45bc74efe76dea21bd789e76d1f37416ad6f30b1 Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Sun, 8 Mar 2015 02:57:37 +1100
Subject: [PATCH] use a lookup table instead of an if - #945

---
 src/babel/build-external-helpers.js | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/src/babel/build-external-helpers.js b/src/babel/build-external-helpers.js
index b96579a27f..b20f956c3b 100644
--- a/src/babel/build-external-helpers.js
+++ b/src/babel/build-external-helpers.js
@@ -56,12 +56,15 @@ export default function (whitelist, outputType = "global") {
   };
 
   var tree;
-  if (outputType === "global") {
-    tree = buildGlobal(namespace, builder);
-  } else if (outputType === "umd") {
-    tree = buildUmd(namespace, builder);
-  } else if (outputType === "var") {
-    tree = buildVar(namespace, builder);
+
+  var build = {
+    global: buildGlobal,
+    umd:    buildUmd,
+    var:    buildVar
+  }[outputType];
+
+  if (builder) {
+    tree = build(namespace, builder);
   } else {
     throw new Error(messages.get("unsupportedOutputType", outputType));
   }