sortdeps.js

const deps1 = {
  mongo: [],
  tzinfo: ['thread_safe'],
  uglifier: ['execjs'],
  execjs: ['thread_safe', 'json'],
  redis: [],
};

const sortDeps = (depsMap) => {
  const reduce = (deps) => deps.reduce(
    (acc, dep) => [
      ...acc,
      ...reduce(depsMap[dep] || []),
      dep
    ],
    []
  );

  return reduce(Object.keys(depsMap))
    .filter((itm, i, array) => array.indexOf(itm) === i);
};

console.log(sortDeps(deps1));
// => ['mongo', 'thread_safe', 'tzinfo', 'json', 'execjs', 'uglifier', 'redis'];