preprocessor.js

// preprocessor.js
var ReactTools = require('react-tools');
module.exports = {
  process: function(src) {
    return ReactTools.transform(src, {
        harmony:true
    });
  }
};

preprocessor1.js

var babel = require("babel");
module.exports = {
    process: function(src, filename) {
        if (!babel.canCompile(filename)) {
          return '';
        }
        if (filename.indexOf('node_modules') === -1) {
          return babel.transform(src, {filename: filename}).code;
        }
        return src;
    }
};