@wuyuchentr/cron-scheduler-lite

Lightweight cron scheduler — zero dependencies, < 2 KB. Supports second-level precision.

Install

npm install @wuyuchentr/cron-scheduler-lite

Usage

const { schedule } = require('@wuyuchentr/cron-scheduler-lite');

// Run at 9:00 AM every day
const job = schedule('0 9 * * *', () => {
  console.log('Time for morning standup!');
});

job.start();

// Later: stop the job
// job.stop();

With seconds (6-field syntax)

// Every 5 seconds
schedule('*/5 * * * * *', () => poll());

// At 09:30:15 every day
schedule('15 30 9 * * *', () => backup());

Cron expression reference (5-field)

┌───────── minute (0-59)
│ ┌───────── hour (0-23)
│ │ ┌───────── day of month (1-31)
│ │ │ ┌───────── month (1-12)
│ │ │ │ ┌───────── day of week (0-6, 0=Sun)
│ │ │ │ │
* * * * *

Supported patterns

| Pattern | Description | |---------|-------------| | * | Every value | | */n | Every n units | | n | Exact value | | n,m | List of values | | n-m | Range |

Examples

schedule('0 9 * * 1-5',   () => console.log('9 AM, weekdays'));
schedule('0 0 * * *',     () => console.log('Midnight'));
schedule('*/15 * * * *',  () => console.log('Every 15 minutes'));
schedule('0 */2 * * *',   () => console.log('Every 2 hours'));
schedule('30 8 1 * *',    () => console.log('8:30 AM on the 1st'));
schedule('* * * * * *',   () => console.log('Every second'));

How it works

• Parses the cron expression into typed fields (all, step, list, range, exact)
• Computes the exact next run time and schedules with setTimeout
• After each run, re-computes the next run (handles DST, clock drift)
• No polling, no setInterval — pure event-driven