node-cron

What is node-cron?

node-cron is a task scheduler for Node.js that allows you to schedule jobs (functions) to run at specific times or intervals using cron syntax. It is useful for automating repetitive tasks such as backups, email notifications, and data processing.

What are node-cron's main functionalities?

Basic Scheduling

This feature allows you to schedule a task to run at specific intervals using cron syntax. In this example, the task runs every minute.

const cron = require('node-cron');

cron.schedule('* * * * *', () => {
  console.log('Running a task every minute');
});

Specific Time Scheduling

This feature allows you to schedule a task to run at a specific time. In this example, the task runs every day at midnight.

const cron = require('node-cron');

cron.schedule('0 0 * * *', () => {
  console.log('Running a task every day at midnight');
});

Task Stopping

This feature allows you to stop a scheduled task. In this example, the task is scheduled to run every minute but is stopped immediately after being scheduled.

const cron = require('node-cron');

let task = cron.schedule('* * * * *', () => {
  console.log('Running a task every minute');
});

task.stop();

Task Starting

This feature allows you to start a scheduled task. In this example, the task is scheduled to run every minute and is started explicitly.

const cron = require('node-cron');

let task = cron.schedule('* * * * *', () => {
  console.log('Running a task every minute');
});

task.start();

Task Destruction

This feature allows you to completely destroy a scheduled task, removing it from the scheduler. In this example, the task is scheduled to run every minute but is destroyed immediately after being scheduled.

const cron = require('node-cron');

let task = cron.schedule('* * * * *', () => {
  console.log('Running a task every minute');
});

task.destroy();

Other packages similar to node-cron

node-schedule

node-schedule is another task scheduler for Node.js that uses a more flexible syntax compared to cron. It allows for more complex scheduling patterns and supports both cron-like syntax and JavaScript date objects. It is more feature-rich but also more complex to use compared to node-cron.

agenda

agenda is a light-weight job scheduling library for Node.js that uses MongoDB for persistence. It is designed for long-running jobs and supports job prioritization, job concurrency, and job locking. It is more suitable for applications that require persistent job storage and more advanced job management features compared to node-cron.

bree

bree is a job scheduler for Node.js that uses worker threads to run jobs in parallel. It supports cron syntax and provides features like graceful shutdown, job retries, and job concurrency. It is more suitable for applications that require parallel job execution and advanced job management features compared to node-cron.

README

Node Cron

The node-cron module is tiny task scheduler in pure JavaScript for node.js based on GNU crontab. This module allows you to schedule task in node.js using full crontab syntax.

Need a job scheduler with support for worker threads and cron syntax? Try out the Bree job scheduler!

Getting Started

Install node-cron using npm:

npm install --save node-cron

Import node-cron and schedule a task:

var cron = require('node-cron');

cron.schedule('* * * * *', () => {
  console.log('running a task every minute');
});

Cron Syntax

This is a quick reference to cron syntax and also shows the options supported by node-cron.

Allowed fields

 # ┌────────────── second (optional)
 # │ ┌──────────── minute
 # │ │ ┌────────── hour
 # │ │ │ ┌──────── day of month
 # │ │ │ │ ┌────── month
 # │ │ │ │ │ ┌──── day of week
 # │ │ │ │ │ │
 # │ │ │ │ │ │
 # * * * * * *

Allowed values

field	value
second	0-59
minute	0-59
hour	0-23
day of month	1-31
month	1-12 (or names)
day of week	0-7 (or names, 0 or 7 are sunday)

Using multiples values

You may use multiples values separated by comma:

var cron = require('node-cron');

cron.schedule('1,2,4,5 * * * *', () => {
  console.log('running every minute 1, 2, 4 and 5');
});

Using ranges

You may also define a range of values:

var cron = require('node-cron');

cron.schedule('1-5 * * * *', () => {
  console.log('running every minute to 1 from 5');
});

Using step values

Step values can be used in conjunction with ranges, following a range with '/' and a number. e.g: 1-10/2 that is the same as 2,4,6,8,10. Steps are also permitted after an asterisk, so if you want to say “every two minutes”, just use */2.

var cron = require('node-cron');

cron.schedule('*/2 * * * *', () => {
  console.log('running a task every two minutes');
});

Using names

For month and week day you also may use names or short names. e.g:

var cron = require('node-cron');

cron.schedule('* * * January,September Sunday', () => {
  console.log('running on Sundays of January and September');
});

Or with short names:

var cron = require('node-cron');

cron.schedule('* * * Jan,Sep Sun', () => {
  console.log('running on Sundays of January and September');
});

Cron methods

Schedule

Schedules given task to be executed whenever the cron expression ticks.

Arguments:

• expression string: Cron expression
• function Function: Task to be executed
• options Object: Optional configuration for job scheduling.

Options

• scheduled: A boolean to set if the created task is scheduled. Default true;
• timezone: The timezone that is used for job scheduling. See IANA time zone database for valid values, such as Asia/Shanghai, Asia/Kolkata, America/Sao_Paulo.

Example:

 var cron = require('node-cron');

 cron.schedule('0 1 * * *', () => {
   console.log('Running a job at 01:00 at America/Sao_Paulo timezone');
 }, {
   scheduled: true,
   timezone: "America/Sao_Paulo"
 });

ScheduledTask methods

Start

Starts the scheduled task.

var cron = require('node-cron');

var task = cron.schedule('* * * * *', () =>  {
  console.log('stopped task');
}, {
  scheduled: false
});

task.start();

Stop

The task won't be executed unless re-started.

var cron = require('node-cron');

var task = cron.schedule('* * * * *', () =>  {
  console.log('will execute every minute until stopped');
});

task.stop();

Validate

Validate that the given string is a valid cron expression.

var cron = require('node-cron');

var valid = cron.validate('59 * * * *');
var invalid = cron.validate('60 * * * *');

Issues

Feel free to submit issues and enhancement requests here.

Contributing

In general, we follow the "fork-and-pull" Git workflow.

• Fork the repo on GitHub;
• Commit changes to a branch in your fork;
• Pull request "upstream" with your changes;

NOTE: Be sure to merge the latest from "upstream" before making a pull request!

Please do not contribute code you did not write yourself, unless you are certain you have the legal ability to do so. Also ensure all contributed code can be distributed under the ISC License.

Contributors

This project exists thanks to all the people who contribute.

Backers

Thank you to all our backers! 🙏 [Become a backer]

Sponsors

Support this project by becoming a sponsor. Your logo will show up here with a link to your website. [Become a sponsor]

License

node-cron is under ISC License.