From 5b08924c026ff21c2857ba5d0f2357eb424ec890 Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Thu, 16 Oct 2014 09:39:52 +1100
Subject: [PATCH] add customisable extensions to require hook #75

---
 README.md            | 20 +++++++++++++++++---
 lib/6to5/register.js | 32 ++++++++++++++++++++++++++++----
 2 files changed, 45 insertions(+), 7 deletions(-)

diff --git a/README.md b/README.md
index 15a651e088..45c25a4aa5 100644
--- a/README.md
+++ b/README.md
@@ -172,8 +172,9 @@ to5.transformFile("filename.js", options, function (err, result) {
 
 #### Require hook
 
-All subsequent files required by node will be transformed by 6to5. The polyfill
-specified in [Polyfill](#polyfill) is also required.
+All subsequent files required by node with the extensions `.es6` and `.js` will
+be transformed by 6to5. The polyfill specified in [Polyfill](#polyfill) is also
+required.
 
 ```javascript
 require("6to5/register");
@@ -183,7 +184,20 @@ require("6to5/register");
 override this by passing an ignore regex via:
 
 ```javascript
-require("6to5/register")(/regex/)
+require("6to5/register")(/regex/);
+```
+
+You can also customise the file extensions that the require hook will use via:
+
+```javascript
+require("6to5/register")({
+  // optional ignore regex
+  ignoreRegex: /regex/,
+
+  // this will remove the currently hooked extensions of .es6 and .js so you'll
+  // have to add them back if you want them to be used again
+  extensions: [".js", ".es6"]
+});
 ```
 
 ### Browser
diff --git a/lib/6to5/register.js b/lib/6to5/register.js
index fcf418eb37..d429c24810 100644
--- a/lib/6to5/register.js
+++ b/lib/6to5/register.js
@@ -2,6 +2,7 @@ require("./polyfill");
 
 var sourceMapSupport = require("source-map-support");
 var to5              = require("./index");
+var _                = require("lodash");
 
 sourceMapSupport.install({
   retrieveSourceMap: function (source) {
@@ -17,12 +18,14 @@ sourceMapSupport.install({
   }
 });
 
+//
+
 var ignoreRegex = /node_modules/;
+var exts        = [];
 var maps        = {};
 var old         = require.extensions[".js"];
 
-require.extensions[".js"] =
-require.extensions[".es6"] = function (m, filename) {
+var loader = function (m, filename) {
   if (ignoreRegex && ignoreRegex.test(filename)) {
     return old.apply(this, arguments);
   }
@@ -36,6 +39,27 @@ require.extensions[".es6"] = function (m, filename) {
   m._compile(result.code, filename);
 };
 
-module.exports = function (_ignoreRegex) {
-  ignoreRegex = _ignoreRegex;
+var hookExtensions = function (_exts) {
+  _.each(exts, function (ext) {
+    delete require.extensions[ext];
+  });
+
+  exts = _exts;
+
+  _.each(exts, function (ext) {
+    require.extensions[ext] = loader;
+  });
+};
+
+hookExtensions([".es6", ".js"]);
+
+module.exports = function (opts) {
+  opts = opts || {};
+  if (_.isRegExp(opts)) opts = { ignoreRegex: opts };
+
+  if (opts.ignoreRegex != null) {
+    ignoreRegex = opts.ignoreRegex;
+  }
+
+  if (opts.extensions) hookExtensions(opts.extensions);
 };