[api] Added `nconf.loadFiles()` method

lib/nconf.js

@@ -5,7 +5,9 @@
  *
  */
 
-var Provider = require('./nconf/provider').Provider,
+var fs = require('fs'),
+    async = require('async'),
+    Provider = require('./nconf/provider').Provider,
     nconf = module.exports = Object.create(Provider.prototype);
 
 //
@@ -35,6 +37,38 @@ nconf.key = function () {
   return Array.prototype.slice.call(arguments).join(':');
 };
 
+//
+// ### function loadFiles (files)
+// #### @files {Array} List of files to load.
+// Loads all the data in the specified `files`.
+//
+nconf.loadFiles = function (files, callback) {
+  if (!files) {
+    return callback(null, {});
+  }
+
+  var allData = {};
+
+  function loadFile (file, next) {
+    fs.readFile(file, function (err, data) {
+      if (err) {
+        return next(err);
+      }
+
+      data = JSON.parse(data.toString());
+      Object.keys(data).forEach(function (key) {
+        allData[key] = data[key];
+      });
+
+      next();
+    });
+  }
+
+  async.forEach(files, loadFile, function (err) {
+    return err ? callback(err) : callback(null, allData);
+  });
+};
+
 //
 // Expose the various components included with nconf
 //