Using node-cron for Scheduled Tasks in Node.js Syntax and Examples

Using node-cron for Scheduled Tasks

node-cron is the most popular cron scheduling library for Node.js. This guide covers syntax, patterns, and examples.

Installation

npm install node-cron

Basic Usage

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

// Schedule a task
const task = cron.schedule("0 0 * * *", () => {
  console.log("Running daily task at midnight");
});

// Stop a task
task.stop();

// Start a stopped task
task.start();

// Destroy a task (cannot be restarted)
task.destroy();

Cron Expression Reference

┌─────────────── minute (0 - 59)
│ ┌─────────────── hour (0 - 23)
│ │ ┌─────────────── day of month (1 - 31)
│ │ │ ┌─────────────── month (1 - 12)
│ │ │ │ ┌─────────────── day of week (0 - 7) (0 or 7 is Sunday)
│ │ │ │ │
* * * * *

Common Patterns

// Every minute
cron.schedule("* * * * *", () => {});

// Every 5 minutes
cron.schedule("*/5 * * * *", () => {});

// Every 15 minutes
cron.schedule("*/15 * * * *", () => {});

// Every hour at minute 0
cron.schedule("0 * * * *", () => {});

// Every day at midnight
cron.schedule("0 0 * * *", () => {});

// Every day at 9 AM
cron.schedule("0 9 * * *", () => {});

// Every Sunday at midnight
cron.schedule("0 0 * * 0", () => {});

// Every weekday (Mon-Fri) at 9 AM
cron.schedule("0 9 * * 1-5", () => {});

// Every month on the 1st at midnight
cron.schedule("0 0 1 * *", () => {});

// Every Monday, Wednesday, Friday at 5 PM
cron.schedule("0 17 * * 1,3,5", () => {});

// Every 6 hours
cron.schedule("0 */6 * * *", () => {});

// Every 30 seconds (node-cron supports seconds)
cron.schedule("*/30 * * * * *", () => {});

Real-World Example: DevTinder Scheduled Tasks

// src/cron/index.js
const cron = require("node-cron");
const User = require("../models/User");
const ConnectionRequest = require("../models/ConnectionRequest");

// 1. Daily cleanup of expired tokens
cron.schedule("0 0 * * *", async () => {
  console.log("Cleaning up expired tokens...");
  await User.updateMany(
    { resetPasswordExpires: { $lt: new Date() } },
    { $unset: { resetPasswordToken: 1, resetPasswordExpires: 1 } }
  );
  console.log("Token cleanup complete");
});

// 2. Send daily digest emails
cron.schedule("0 9 * * *", async () => {
  console.log("Sending daily digest emails...");
  const users = await User.find({ emailBounced: false });
  for (const user of users) {
    const pendingRequests = await ConnectionRequest.countDocuments({
      toUserId: user._id,
      status: "interested",
      createdAt: { $gte: new Date(Date.now() - 24 * 60 * 60 * 1000) }
    });
    if (pendingRequests > 0) {
      await sendEmail(user.email, "dailyDigest", {
        firstName: user.firstName,
        pendingRequests
      });
    }
  }
  console.log("Digest emails sent");
});

// 3. Weekly inactive user cleanup
cron.schedule("0 0 * * 0", async () => {
  console.log("Cleaning up inactive users...");
  const thirtyDaysAgo = new Date(Date.now() - 30 * 24 * 60 * 60 * 1000);
  await User.deleteMany({
    isVerified: false,
    createdAt: { $lt: thirtyDaysAgo }
  });
  console.log("Inactive users cleaned up");
});

// 4. Hourly stats logging
cron.schedule("0 * * * *", async () => {
  const userCount = await User.countDocuments();
  const connectionCount = await ConnectionRequest.countDocuments();
  console.log(`Stats: ${userCount} users, ${connectionCount} connections`);
});

Timezone Support

// Run at 9 AM in a specific timezone
cron.schedule("0 9 * * *", () => {
  console.log("Running at 9 AM IST");
}, {
  timezone: "Asia/Kolkata"
});

Scheduled Job Options

const task = cron.schedule("0 0 * * *", () => {
  console.log("Running task");
}, {
  scheduled: true,    // Start immediately (default: true)
  timezone: "UTC",    // Timezone for the cron expression
  name: "DailyCleanup" // Optional name for debugging
});

// Start later
task.start();

// Stop
task.stop();

Validating Cron Expressions

// Check if a cron expression is valid
const isValid = cron.validate("0 0 * * *");
console.log(isValid); // true

const isInvalid = cron.validate("invalid");
console.log(isInvalid); // false

The Takeaway

node-cron provides flexible cron scheduling in Node.js. Use cron expressions (minute hour day month weekday) to schedule tasks at any interval. Common patterns include daily at midnight (0 0 * * ), every 15 minutes (/15 * * * *), and weekdays at 9 AM (0 9 * * 1-5). Use timezone option for location-specific scheduling, validate expressions with cron.validate, and use start/stop/destroy for task management.