docs: function getExternals() {
      var fs = require('fs');
      var nodeModules = {};
  
      fs.readdirSync('node_modules').forEach(function (module) {
        if (module !== '.bin') {
          nodeModules[module] = true;
        }
      });
  
      var nodeModulesTransform = function(context, request, callback) {
        // search for a '/' indicating a nested module
        var slashIndex = request.indexOf("/");
        var rootModuleName;
        if (slashIndex == -1) {
          rootModuleName = request;
        } else {
          rootModuleName = request.substr(0, slashIndex);
        }
  
        // Match for root modules that are in our node_modules
        if (nodeModules.hasOwnProperty(rootModuleName)) {
          callback(null, "commonjs " + request);
        } else {
          callback();
        }
      };
      return nodeModulesTransform;
  }