async_await_notes.js

// Function creation && Process Array in Sequence
const stopRDSMySQL = async ({DBInstanceIdentifier}) => {
  try {
    const rds = new AWS.RDS();
    const {DBInstances} = await rds.describeDBInstances({DBInstanceIdentifier}).promise();
    const listOfStoppedDBInstances = [];
    if(!_.isEmpty(DBInstances)) {
      for(const DBInstance of DBInstances) {
        const {DBInstanceStatus, DBInstanceIdentifier} = DBInstance;
        if(DBInstanceStatus === 'available') {
          console.log(`Gonna stop ${MODULE_NAME}.stopRDSMySQL.dbInstance.${DBInstanceIdentifier}:`);
          listOfStoppedDBInstances.push(DBInstanceIdentifier);
        }
      }
    }
    return listOfStoppedDBInstances;
  } catch(err) {
    throw new Error(`${MODULE_NAME}.stopRDSMySQL: ${err.method}`);
  }
};

// Function creation and process array in parallel
const stopRDSMySQL = async ({DBInstanceIdentifier}) => {
  try {
    const rds = new AWS.RDS();
    const {DBInstances} = await rds.describeDBInstances({DBInstanceIdentifier}).promise();
    const listOfStoppedDBInstances = [];
    if(!_.isEmpty(DBInstances)) {
      await Promise.all(DBInstances.map(DBInstance => {
        const {DBInstanceStatus, DBInstanceIdentifier} = DBInstance;
        if(DBInstanceStatus === 'available') {
          console.log(`Gonna stop ${MODULE_NAME}.stopRDSMySQL.dbInstance.${DBInstanceIdentifier}:`);
          listOfStoppedDBInstances.push(DBInstanceIdentifier);
        }
      }));
    }
    return listOfStoppedDBInstances;
  } catch(err) {
    throw new Error(`${MODULE_NAME}.stopRDSMySQL: ${err.method}`);
  }
};