Package Exports

pnscheduler
pnscheduler/dist/index.js

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Readme

PNScheduler

Persistent NodeJS Scheduler - A simple job scheduler for Node.js applications, with Postgres-based persistence.

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Installation

$ npm install pnscheduler

Features

Schedule jobs at a specific time
Jobs persist between restarts
Configurable grace periods

Set Up

First of all, set the PGCONNECTIONSTRING environment variable for your Postgres database:

#.env
PGCONNECTIONSTRING=<connection_string>

Secondly, run the migration script to create the database tables:

$ node --env-file=.env node_modules/pnscheduler/dist/db/migrationScript.js

Quick Start

Just define a job, schedule it, and start the scheduler.

import scheduler from 'pnscheduler';

// Define a simple job
scheduler.defineJob("greeting", () => {
  console.log("Hello, world!");
});

// Schedule it for tomorrow
await scheduler.scheduleJob("greeting", new Date(Date.now() + 86400000));

// Start the scheduler
scheduler.start();

Usage Examples

Defining Jobs

// Job without parameters
scheduler.defineJob("simple-job", () => {
  console.log("Hello without params!");
});

// Job with parameters
scheduler.defineJob("parameterized-job", 
  ({ something }: { something: string }) => {
    console.log(something);
  }
);

Scheduling Jobs

// Basic scheduling
await scheduler.scheduleJob("simple-job", new Date(2084, 0, 1));

// With parameters
await scheduler.scheduleJob("parameterized-job", new Date(2084, 0, 1), {
  something: "Hello, world!"
});

// With grace period (5 minutes)
await scheduler.scheduleJob("simple-job", new Date(2084, 0, 1), null, 300);

Job Management

// Unscheduling a job
const job = await scheduler.scheduleJob("simple-job", new Date(2084, 0, 1));
await scheduler.unscheduleJob(job);

// Manual job execution
await scheduler.executeJob(job);

// Finding scheduled jobs
const scheduledJobs = await scheduler.findScheduledJobs();
console.log(scheduledJobs);

// Finding due jobs
const dueJobs = await scheduler.findDueJobs();
console.log(dueJobs);

Scheduler Control

// Adjust check frequency (defaults to 1 second)
scheduler.start(30); // check every 30 seconds

// Stop the scheduler
scheduler.stop();

API Reference

Scheduler Methods

defineJob(name: string, handler: Function): void
scheduleJob(name: string, date: Date, params?: any, gracePeriod?: number): Promise<Job>
unscheduleJob(job: Job): Promise<void>
executeJob(job: Job): Promise<void>
findScheduledJobs(): Promise<Job[]>
start(interval: number): void
stop(): void

Scheduler Properties

jobRegistry - As an alternative to defineJob, you can also define jobs by assigning directly to this property,
e.g. scheduler.jobRegistry = {"job-name", () => {}}.
verbose - Set this to true to enable verbose logging,
e.g. scheduler.verbose = true;

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

MIT License