Cron Jobs Summary and Checklist Complete Guide for Node.js Scheduled Tasks

Cron Jobs Summary and Checklist

This is a complete summary of everything you need to know about cron jobs in Node.js.

Cron Job Setup Checklist

• Install node-cron (npm install node-cron)
• Create a cron jobs module (src/cron/index.js)
• Schedule all recurring tasks with cron expressions
• Wrap each job in try-catch
• Log job start, completion, and errors
• Track job execution in a database
• Send alerts on failure
• Set timeouts for each job
• Make jobs idempotent
• Handle timezones
• Prevent overlapping runs
• Test each job independently
• Document all jobs in a registry

Cron Expression Cheat Sheet

* * * * *  - Every minute
*/5 * * * *  - Every 5 minutes
*/15 * * * *  - Every 15 minutes
*/30 * * * *  - Every 30 minutes
0 * * * *  - Every hour
0 */6 * * *  - Every 6 hours
0 0 * * *  - Every day at midnight
0 9 * * *  - Every day at 9 AM
0 0 * * 0  - Every Sunday at midnight
0 0 * * 1  - Every Monday at midnight
0 9 * * 1-5  - Weekdays at 9 AM
0 0 1 * *  - First of every month at midnight
0 0 1 1 *  - January 1st at midnight

Architecture Summary

node-cron (in-app)
├── Data cleanup (daily at midnight)
├── Digest emails (daily at 9 AM)
├── Weekly reports (Monday at midnight)
├── Health checks (every 5 minutes)
└── Cache warming (daily at 5 AM)

PM2 cron (separate scripts)
├── Database backup (daily at 2 AM)
├── Log rotation (weekly on Sunday)
└── System health check (every 15 minutes)

Code Template

// src/cron/index.js
const cron = require("node-cron");
const { runCronJob } = require("./utils");
const { cleanup, sendDigest, generateReport, healthCheck } = require("./jobs");

// Daily cleanup at midnight UTC
cron.schedule("0 0 * * *", () => {
  runCronJob("daily-cleanup", cleanup);
}, { timezone: "UTC" });

// Daily digest at 9 AM IST
cron.schedule("0 9 * * *", () => {
  runCronJob("daily-digest", sendDigest);
}, { timezone: "Asia/Kolkata" });

// Weekly report on Monday at midnight
cron.schedule("0 0 * * 1", () => {
  runCronJob("weekly-report", generateReport);
}, { timezone: "UTC" });

// Health check every 5 minutes
cron.schedule("*/5 * * * *", () => {
  runCronJob("health-check", healthCheck);
});

console.log("Cron jobs scheduled");

// src/cron/utils.js
const isRunning = {};

const runCronJob = async (jobName, jobFn) => {
  if (isRunning[jobName]) {
    console.log(`[${jobName}] Already running, skipping`);
    return;
  }
  
  isRunning[jobName] = true;
  const startTime = Date.now();
  
  try {
    console.log(`[${jobName}] Started`);
    const result = await jobFn();
    const duration = Date.now() - startTime;
    console.log(`[${jobName}] Completed in ${duration}ms`);
    
    await CronJob.create({
      jobName, status: "completed",
      startTime: new Date(startTime), duration, result
    });
  } catch (err) {
    const duration = Date.now() - startTime;
    console.error(`[${jobName}] Failed after ${duration}ms:`, err.message);
    
    await CronJob.create({
      jobName, status: "failed",
      startTime: new Date(startTime), duration,
      error: err.message, errorStack: err.stack
    });
    
    await sendAlert(`[${jobName}] Failed: ${err.message}`);
  } finally {
    isRunning[jobName] = false;
  }
};

module.exports = { runCronJob };

The Takeaway

Cron jobs are essential for recurring tasks in Node.js. Use node-cron for app-integrated tasks (cleanup, notifications, reports) and PM2 cron for independent server tasks (backups). Always wrap in try-catch, log everything, track execution in a database, send alerts on failure, make jobs idempotent, set timeouts, handle timezones, prevent overlapping runs, and document all jobs. Test each job independently before deploying.