@ima-worldhealth/cron-scheduler

cron-scheduler

This is a fork of rstacruz/cron-scheduler. Props to them for their work.

Runs jobs in periodic intervals

cron-scheduler is a way to run functions at specific times of the day. It runs in Node.js as well as the browser.

It requires a Promise implementation to work. If you're on Node.js v4 or later, you should be fine. Otherwise, you'll also need to install bluebird (or rsvp, when, or q.js).

cron()

cron(options, function)

Starts a cronjob.

var cron = require('cron-scheduler')

cron({ on: '0 9 * * *' }, function () {
  console.log('this will run every 9:00am')
})

Options

The options parameter is an object with these things:

• on (String, required) - the schedule in cron format (min hour day month day-of-week).
• timezone (String) - the timezone to run it in.
• name (String) - identifier to show in the debug logs. Means nothing if debugging is off.

cron({
  timezone: 'Asia/Manila'
  on: '0 9 * * *',
  name: 'dostuff'
} , function () {
  console.log('this will run every 9:00am')
})

Cron strings

The options.on parameter is in cron standard format. Check the cron cheatsheet for more details. Here are some examples:

0 9 * * *    - every 9:00AM
0 12 * * 1   - every 12:00PM on mondays
0 */2 * * *  - every 2 hours

Errors

Any errors will be thrown, and will stop the scheduler. If this is not what you want, you may wish to decorate the function being passed.

cron({ on: '0 9 * * *' }, trap(work))

function trap (fn) {
  return function () {
    return Promise.resolve(fn.apply(this, arguments))
      .catch(function (err) {
        // do stuff.
        // this handler will work for both promise rejections
        // *and* regular errors.
      })
  }
}

Promises

If function returns a Promise, it will wait for it to finish before scheduling the next job. If the promise is rejected, it will be an unhandled rejection (!). You may use the same trap() decorator trick above to get around this.

Stopping

To stop the cronjob, just run the stop method returned by cron().

job = cron({ on: '0 12 * * *' }, work)
job.stop()

Manually starting

To manually invoke the cronjob, run the run method returned by cron(). This will not stop the next scheduled invocation.

job = cron({ on: '0 12 * * *' }, work)
job.run()

cron.debug

cron.debug(function)

Sets the debug function.

cron.debug(console.log.bind(console))

You can pass your custom logger here. For instance, you can use the debug module for prettier messages.

cron.debug(require('debug')('cron'))

Thanks

cron-scheduler © 2016+, Rico Sta. Cruz. Released under the MIT License.
Authored and maintained by Rico Sta. Cruz with help from contributors (list).

ricostacruz.com  ·  GitHub @rstacruz  ·  Twitter @rstacruz