Use require instead of requireFromString.

Although there's some niceness in using the string data straight from the filesystem, you lose the ability to use anything that hooks into the native `require` call – namely `babel` and friends. By using vanilla `require` it becomes possible to use ES6 files for your configuration (or indeed anything else that hooks into standard node module loading machinery). Performance-wise the change should be negligible, given the filesystem/stat cache will be hot from having just loaded the contents of the file.

lib/loadDefinedFile.js

@@ -2,8 +2,8 @@
 
 var yaml = require('js-yaml');
 var parseJson = require('parse-json');
-var requireFromString = require('require-from-string');
 var readFile = require('./readFile');
+var irequire = require('./require');
 
 module.exports = function (filepath, options) {
   return readFile(filepath, { throwNotFound: true }).then(function (content) {
@@ -16,7 +16,7 @@ module.exports = function (filepath, options) {
             filename: filepath,
           });
         case 'js':
-          return requireFromString(content, filepath);
+          return irequire(filepath);
         default:
           return tryAllParsing(content, filepath);
       }
@@ -37,7 +37,7 @@ module.exports = function (filepath, options) {
 
 function tryAllParsing(content, filepath) {
   return tryYaml(content, filepath, function () {
-    return tryRequire(content, filepath, function () {
+    return tryRequire(filepath, function () {
       return null;
     });
   });
@@ -57,9 +57,9 @@ function tryYaml(content, filepath, cb) {
   }
 }
 
-function tryRequire(content, filepath, cb) {
+function tryRequire(filepath, cb) {
   try {
-    return requireFromString(content, filepath);
+    return irequire(filepath);
   } catch (e) {
     return cb();
   }

lib/loadJs.js

@@ -1,14 +1,14 @@
 'use strict';
 
-var requireFromString = require('require-from-string');
 var readFile = require('./readFile');
+var irequire = require('./require');
 
 module.exports = function (filepath) {
   return readFile(filepath).then(function (content) {
     if (!content) return null;
 
     return {
-      config: requireFromString(content, filepath),
+      config: irequire(filepath),
       filepath: filepath,
     };
   });

lib/loadRc.js

@@ -2,8 +2,8 @@
 
 var yaml = require('js-yaml');
 var parseJson = require('parse-json');
-var requireFromString = require('require-from-string');
 var readFile = require('./readFile');
+var irequire = require('./require');
 
 module.exports = function (filepath, options) {
   return loadExtensionlessRc().then(function (result) {
@@ -68,7 +68,7 @@ module.exports = function (filepath, options) {
         if (content.config) return content;
         var successFilepath = filepath + '.js';
         return {
-          config: requireFromString(content, successFilepath),
+          config: irequire(filepath),
           filepath: successFilepath,
         };
       }

lib/require.js

@@ -0,0 +1,6 @@
+'use strict';
+
+module.exports = function (path) {
+  var obj = require(path);
+  return obj && obj.__esModule ? obj['default'] : obj;
+};

package.json

@@ -36,8 +36,7 @@
     "minimist": "^1.2.0",
     "object-assign": "^4.1.0",
     "os-homedir": "^1.0.1",
-    "parse-json": "^2.2.0",
-    "require-from-string": "^1.1.0"
+    "parse-json": "^2.2.0"
   },
   "devDependencies": {
     "ava": "0.16.0",