open and save json file

function readFile(filename, content) {
  fs.readFile(filename, function(err, data) {
    if (err) throw err;
    console.log('File saved!');
  });
}

function writeFile(filename, content) {
  fs.writeFile(filename, content, function(err) {
    if (err) throw err;
    console.log('File saved!');
  });
}