module: strip byte order marker when loading *.js and *.json files

BOMs make V8 raise a 'SyntaxError: Unexpected token ILLEGAL' exception.

Fixes nodejs#1440.

lib/module.js

@@ -416,23 +416,35 @@ Module.prototype._compile = function(content, filename) {
   return compiledWrapper.apply(self.exports, args);
 };
 
+
+function stripBOM(content) {
+  // Remove byte order marker. This catches EF BB BF (the UTF-8 BOM)
+  // because the buffer-to-string conversion in `fs.readFileSync()`
+  // translates it to FEFF, the UTF-16 BOM.
+  if (content.charCodeAt(0) === 0xFEFF) {
+    content = content.slice(1);
+  }
+  return content;
+}
+
+
 // Native extension for .js
 Module._extensions['.js'] = function(module, filename) {
   var content = NativeModule.require('fs').readFileSync(filename, 'utf8');
-  module._compile(content, filename);
-};
-
-
-// Native extension for .node
-Module._extensions['.node'] = function(module, filename) {
-  process.dlopen(filename, module.exports);
+  module._compile(stripBOM(content), filename);
 };
 
 
 // Native extension for .json
 Module._extensions['.json'] = function (module, filename) {
   var content = NativeModule.require('fs').readFileSync(filename, 'utf8');
-  module.exports = JSON.parse(content);
+  module.exports = JSON.parse(stripBOM(content));
+};
+
+
+//Native extension for .node
+Module._extensions['.node'] = function(module, filename) {
+  process.dlopen(filename, module.exports);
 };
 
 

test/fixtures/utf8-bom.js

@@ -0,0 +1 @@
+module.exports = 42;

test/fixtures/utf8-bom.json

@@ -0,0 +1 @@
+42

test/simple/test-module-loading.js

@@ -221,3 +221,8 @@ process.addListener('exit', function() {
 
   console.log('exit');
 });
+
+
+// #1440 Loading files with a byte order marker.
+assert.equal(42, require('../fixtures/utf8-bom.js'));
+assert.equal(42, require('../fixtures/utf8-bom.json'));