From 0946f82d9d7fd2784cba823776330b9dc424aabd Mon Sep 17 00:00:00 2001
From: Dominique Busser <doque@users.noreply.github.com>
Date: Wed, 27 Apr 2016 20:18:18 +0200
Subject: [PATCH] fix: strip any duplicate extensions from --extension (#237)

---
 index.js | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/index.js b/index.js
index d35a5c7cf..4f72eec28 100755
--- a/index.js
+++ b/index.js
@@ -58,6 +58,9 @@ function NYC (opts) {
 
   this.extensions = arrify(config.extension).concat('.js').map(function (ext) {
     return ext.toLowerCase()
+  }).filter(function (item, pos, arr) {
+    // avoid duplicate extensions
+    return arr.indexOf(item) === pos
   })
 
   this.transforms = this.extensions.reduce(function (transforms, ext) {