npm install --save nconf

const nconf = require('nconf');
nconf.file({ file: getUserHome() + 'config.json' });

function saveSetting(settingKey, settingValue) {
  nconf.set(settingKey, settingValue);
  nconf.save();
}

function readSetting(settingKey) {
  nconf.load();
  return nconf.get(settingKey);
}

function getUserHome() {
  return process.env[(process.platform == 'win32') ? 'USERPROFILE' : 'HOME'];
}
module.exports = {
  saveSetting: saveSetting,
  readSetting: readSetting
}

const config = require('config');
var size = config.readSetting('Size');
if(!size){  //如果读取不到，设置一个
config.saveSetting('color',['500','500']);
}