form-data/lib/populate.js

A library to create readable "multipart/form-data" streams. Can be used to submit forms and file uploads to other web applications.

// populates missing values
module.exports = function(dst, src) {

  Object.keys(src).forEach(function(prop)
  {
    dst[prop] = dst[prop] || src[prop];
  });

  return dst;
};