- About
- Installation
- Examples
- Usage
- Mocking
- Documentation

About

- Node.js object wrapper for unref'ed setInterval.
- weak means it will not prevent Node.js process to exit if event loop is empty.
- It will help you remember about routine context.
- No external dependencies.

Installation

Requires Node.js v4.8.7
``sh
$ npm install weak-daemon
`

Examples

- Ordinary function:
`js
const WeakDaemon = require('weak-daemon').WeakDaemon

var daemon = new WeakDaemon(
102,
null,
() => { console.log('tick', 'tock') }
);

daemon.start(); // Will print 'tick' 'tock' every ~102 ms

..

/ (!) Note that multiple 'start' call without previous 'stop' will throw error /
daemon.start(); // First call made after ~102ms
daemon.start(false);// First call made after ~102ms
daemon.start(true); // First call made immediately;

..

daemon.start();
daemon.isRunning(); // true
daemon.stop();
daemon.isRunning(); // false
daemon.start();
`

- Equivalent of above example
`js
var daemon = new WeakDaemon(
102,
null,
console.log,
['tick', 'tock']
);
`


- Function that requires a caller context, because of this usage:
`js
const worker = {
data: {},
updateData(source) {
this.data = source.data;
}
}

var daemon = new WeakDaemon(
102,
worker, / So this will be handled properly on updateData call /
worker.updateData,
[data_source]
);

daemon.start();
`

- Example error scenario:
`js
const worker = {
data: {},
source: {...},

updateData() {
this.data = this.source.data()
}
}

var daemon = new WeakDaemon(
101,
null, / this.source will be undefined while daemon will call updateData /
worker.updateData
);

/ Error - this.source is undefined /
daemon.start();
`

Mocking for test purposes:

`js
/ your-lib.js /
const {getInstance} = require('weak-daemon');

// :(
const non_mockable_daemon = new WeakDaemon(...args);

// :)
const mockable_daemon = getInstance(...args);
`
`js
/ test-your-lib.js /
const WD = require('weak-daemon');

WD.getInstance = () => { return your_mock; }
`
Alternative way:
`js
/ your-lib.js /
const {WeakDaemon, getClass} = require('weak-daemon');

const non_mockable_daemon = new WeakDaemon(...args)

const MockableWeakDaemon = getClass();
const mockable_daemon = new MockableWeakDaemon(...args);
`
`js
/ test-your-lib.js /
const WD = require('weak-daemon');

WD.getClass = () => { return YourMock; }
`

Documentation

$3

- ##### constructor( interval_time, caller, task, task_args=[] )
###### Arguments:
- interval integer number - interval time of task call in milliseconds. Note this is not guarntee to call task every interval, it works exactly the same as setInterval(..).unref()
- caller object | null - task's caller context (in case if task will use 'this' keyword)
- task function - task that will be called every interval
- [task_args] Array - list of arguments task will be called with.

- ##### start( immediate_call )
Start daemon.
###### Arguments:
- immediate_call - boolean, is task should be called immediately after start call. Default false.

- ##### stop()
Stop daemon (can be resterted by calling start).

- ##### isRunning()
###### Returns:
- boolean, is daemon running

- ##### interval getter for provided interval_time
- ##### caller getter for provided caller
- ##### task getter for provided task
- ##### args getter for provided args ([] returned if not provided])

$3

Provided for mocking purposes.
- ###### Arguments: @see class WeakDaemon` constructor
- ###### Returns: instance of WeakDaemon.

$3

Provided for mocking purposes.
- ###### Arguments: no
- ###### Returns: WeakDaemon class.