Node Queue Runner

A class to facilitate queuing and running jobs. Right now it only implements a synchronous queue, but it might be extended in the future to enable async jobs.

Basic Usage

First install: npm install --save node-queue-runner

This class is meant to be extended (think of an abstract class in other languages).

const JobQueue = require('node-queue-runner');

class MyJobQueue extends JobQueue {

    runJob(job) {

        return new Promise( ... );
    }
}

const myJobs = new MyJobQueue(startDelay);

myJobs.addJob('Whatever your runJob method expects. Must be truthy');

myJobs.on('jobFinish', (job, jobQueue) => {
    console.log(job + ' just finished.');
    console.log('Now the queue looks like this: ' + jobQueue);
});

myJobs.on('queueEmpty', () => {
    console.log('Queue is now empty.');
});

Subclasses are expected to override the runJob() method. That method must return a Promise that resolves when the job is finished (or rejects on errors).

API Details

The constructor takes the following arguments:

• startDelay (optional, default: 0): Wait this many milliseconds before starting the first job. After the first job has started there is no delay between jobs.
• jobDelay (optional, default: 0): Wait this many milliseconds in between jobs as we process the queue.
• autoStart (optional, default: false): Starts the queue as soon as a job is added. If false, the queue will need to be manually started a first time, then every time the queue is emptied (ie when queueEmpty has fired).

The class emits the following events that you can listen for.

• jobStart: Triggered when a queued job starts. Listener args: (job, jobQueue)
• jobFinish: Triggered when a job completes. Listener args: (job, jobQueue)
• jobAdd: Triggered when a job is added to the queue. Listener args: (job, jobQueue)
• jobRemove: Triggered when a job is removed from the queue. Listener args: (jobQueue)
• queueError: Triggered when a job Promise rejects or when other errors occur. Listener args: (error, jobQueue)
• queueEmpty: Triggered when the queue empties.

The only "public" methods are:

• startJobs: manually starts to process the queue.
• addJob: Pass in anything (string, object, function, etc.) that your runJob method expects to process. Must be a truthy value (i.e. jobs.addjob(0) will fail).
• getQueue: Returns an array of jobs currently in the queue.

Credits

• Node Job Queue by Dominic P