antd-theme-generator/node_modules/form-data/lib/populate.js

This a script to generate color specific styles less file and which you can use to change theme dynamically in browser

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

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

  return dst;
};