Cron Job in Nodejs

In this blog, we will learn how to create a cron job in nodejs. For this, we will be using node package node-cron. Source code of this package can be found on Github using this link.

So lets get started with it. First install node-cron as under

npm install --save node-cron

Then, in the code, import this package as

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

and then you can schedule cron jobs as

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

In the above example, we create a cron job and parameter passed to schedule function are * * * * * * . Explanation of this is as

Values allowed

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)

Operators than can be used

Operator	Usage
/	for step values
,	value list separator
–	range of values

These operators have been explained in the Examples section.

Examples of Cron Job in NodeJS

Run cron job every day at 10:30:20 AM

cron.schedule("20 30 10 * * *", () => {
    console.log("running a task everyday at 10:30am");
  });

Run cron job on the first of every month

cron.schedule("0 0 1 * *", () => {
    console.log("running a task on the 1st of every month at 00:00");
  });

Run cron job every hour

cron.schedule("0 * * * *", () => {
    console.log("running a task hourly");
  });

There is another way for doing so.

‘/’ operator helps you to get step values as illustrated in the table earlier. It can be used in the following way. If you want a cron job to run every hour, you can write */1 in the place holder for an hour. Similarly, you can write */5 in the place holder for an hour if you want the cron job to run every 5 hours. Example of running cron job every hour is here:

cron.schedule(" 0 */1 * * *", () => {
    console.log("running a task hour");
  });

Run cron job after every 10 mins

cron.schedule(" */10 * * * *", () => {
    console.log("running a task hour");
  });

Run cron job on a particular date

cron.schedule(" 0 0 1 11 *", () => {
    console.log("runs the task on 1st November at 00:00 hrs every year");
  });

Run cron job using multiple values

Lets say you want to run a cron job on 1,2,4 and 5 minute:

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

Run cron job using a range

If you want a cron job to run from every minute 1-5.

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

Run cron using name

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

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

or we can also use short names

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

Happy Scheduling!