Executable script, takes in target json file, output json file, and a string of the json path you want to export, like 'parent.child.child'

json-path-export.js

#!/usr/bin/env node

const fs = require('fs');
const path = require('path');

const from = JSON.parse(fs.readFileSync(path.resolve(process.argv[2])).toString());
const to = path.resolve(process.argv[3]);
const jsonPath = process.argv[4].split('.');

function getValueFromPaths(paths, object) {
  if (paths.length === 1) {
    return object[paths[0]];
  }
  const attribute = paths.shift();
  return getValueFromPaths(paths, object[attribute]);
}

fs.writeFileSync(to, JSON.stringify(getValueFromPaths(jsonPath, from)));