js-event-tracker

Summary

This utility helps record and search # of events in the past x seconds. It can be used to log each event as a count in memory and retrieve the # of events for a requested span of seconds in the past.

defaults (set in src/config.ts file):

• Up to 5 minutes in the past (configurable with maxTimeSpan)
• Up to 10 buckets over the span of 5 minutes
• Garbage collection occurs on an interval of every 2.5 minutes

Build/Compile

This command will output to the ./dist directory

npm run build

Basic Usage

/* import EventTracker from 'js-event-tracker'; */
import EventTracker from './js-event-tracker/dist';

const myEventTracker = new EventTracker({
    name: 'my-event-tracker'
});

function myEvent() {
    myEventTracker.add();
    console.log('This is a mock event');
}

myEvent();
myEvent();
myEvent();

setTimeout(() => {
    myEvent();
}, 1000);

setTimeout(() => {
    myEvent();
}, 5000);

setTimeout(() => {
    myEventTracker.getEventCount(3); // 3 seconds in the past, returns a count of 4
}, 2000);


setTimeout(() => {
    myEvent();
    myEventTracker.getEventCount(10); // 10 seconds in the past, returns a count of 6
    myEventTracker.getEventCount(2); // 1 seconds in the past, returns a count of 1
}, 6000);

Additional Documentation/Notes

• Options interface for class constructor:

interface IEventTrackerOptions extends IEventTrackerBaseOptions {
    gcIntervalMs?: number;
    maxBucketSize?: number;
    maxTimeSpan?: number;
    store?: any;
}
export interface IEventTrackerBaseOptions {
    name: string;
}

const exampleEventTracker = new EventTracker(options: IEventTrackerOptions);

• name is the only required property
• Use eventTracker.id to get a uuid for the tracker or eventTracker.name to get the name you have applied to the tracker
• The EventTracker class has a built in garbage collector that runs on a setInterval. After a tracker is no longer needed, it's imported to clear the interval by calling eventTracker.stopGarbageCollection(). This will remove any closure that would otherwise keep the class around in memory.

Testing

Run Unit Tests

Tests will compile any code changes in ./src before running.

Run all tests (w/ coverage)

npm run test

Run unit tests only:

npm run test:unit

Run unit tests only, and with coverage:

npm run test:unit:coverage

Run some basic benchmark/scale tests

npm run test:scale

Begin the stress tests and load chrome://inspect in the browser. This will allow live inspection through chrome dev-tools. Here we can check for a memory leak, check the console for a recurring log of the count, gather heap snapshots, etc.

npm run test:stress