Node.js Web Server in Practice: Scheduled Tasks

Preface

Scheduled tasks are an essential capability in server-side development.

In Node.js web server development,

you can use cron to implement scheduled tasks.

qiao-timer

You can refer to the official documentation for cron usage.

Here is a packaged npm module for convenience: https://code.insistime.com/#/qiao-timer

Usage is simple:

1. Configure a cron-compliant time expression

2. Set the function to be executed on schedule

const { run } = require('qiao-timer');

const time = '*/1 * * * * *';
const tick = () => {
  console.log(new Date());
};

console.log('-' + new Date());
run(time, tick);

The time follows the cron specification.

The common cron specification has 5 fields.

Here, the cron npm package uses a 6-field time specification,

where the first field is seconds, following the same rules as the other fields.

For quick cron editing, you can use this website: https://crontab.guru/

Enter a rule and it will show the actual execution schedule.

For example, entering:

5 4 * * *

It will indicate execution at 4:05 AM every day.

Using in qiao-z

qiao-z is a minimalist Node.js web server framework.

See: https://qiao-z.vincentqiao.com/#/

In qiao-z, you can conveniently use qiao-timer to implement scheduled tasks.

1. Pass in the cron plugin during initialization

// options
const options = {
  cron: require('qiao-timer'),
};

// app
const app = qz(options);

2. Create *Task.js files. qiao-z will automatically scan files ending with Task.js on startup.

exports.time = '*/1 * * * * *';
exports.tick = function () {
  console.log(1);
};

As shown above, this is a scheduled task that executes every second, printing a log.

3. If you need to execute the task immediately once, you can use the following code:

exports.runAndInit = true;
exports.time = '*/1 * * * * *';
exports.tick = function () {
  console.log(1);
};

Summary

1. Introduction to cron, https://www.npmjs.com/package/cron

2. Introduction to qiao-timer, https://code.insistime.com/#/qiao-timer

3. Using the qiao-timer plugin in qiao-z, https://qiao-z.vincentqiao.com/#/plugins/cron