Run cron job in nodejs

Question

I have this simple cron job function:

var job = new cronJob('* * * * * *', function () {
  // do some form of stuffs...
 }, function () {
     console.log('DelCron Job finished.');
 }, true, 'Asia/Calcutta');

This will run every second.

My question:

In the mysql database i have one table called "profsms" in this table i have scheduledTime field.

If scheduledTime = 18/01/2018 10.00AM

I want to run that cron job by that time dynamically is it possible?

Answer 1

You just need to change your time to the cronjob schedule string.

Assuming the string to look like this

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

Since you have (dd/mm/yyyy hour.minute(AM/PM)) (18/01/2018 10.00AM)

const convertTimeToCronJobString = (time) => {
    let retString = '';
    const dmy = time.split(' ')[0];
    const d = dmy.split('/')[0];
    const m = dmy.split('/')[1];
    const y = dmy.split('/')[2];

    const hm = time.split(' ')[1];
    const h = hm.split(';')[0];
    let min = '';
    if (hm.split(';')[1].indexOf('AM') > -1) { // AM
      min = hm.split(';')[1].replace('AM','');
    } else if (hm.split(';')[1].indexOf('AM') > -1) { // PM
      min = hm.split(';')[1].replace('PM','');
      min = String(Number(min) + 12);
    }
    return `0 ${min} ${h} ${d} ${m} ${y}` // you want to start at 0th secound
}

Now you just need to send your scheduledTime into this function and that will return you a cronjobString. Use that string to schedule your task.