covjs

A super lightweight pubsub module. Around 1Kb minified, ~500B minified and gzipped.

Cov is short for covenants.

How to use

Install

• NPM: npm install covjs

Import the module

A global cov object is exported for quick and convienient usage.

var { cov } = require('covjs');

If you require multiple instances or other complex use-cases, a Covenant function is exported so you can create your own cov object.

var { Covenant } = require('covjs');
var cov = new Covenant();

Subscribe to a covenant

// Subscribe to the 'Cov-Name' covenant, execute function when signaled
cov.on('Cov-Name', function(arg1, arg2) {
    var data = {
        foo: arg1,
        bar: arg2
    };

    doSomething(data)
});

Subscribe to a covenant only once

// Function will only fire for first signal of 'Cov-Name'.
cov.once('Cov-Name', function(arg1, arg2) {
    var data = {
        foo: arg1,
        bar: arg2
    };

    doSomethingOnce(data)
});

Signal a covenant (publish)

// Signal this covenant with 2 arguments
cov.signal('Cov-Name', ['argument 1', 'argument 2']);

Unsubscribe all from a Covenant

To unsubscribe all listeners from a Covenant:

// unsubscribe from 'Cov-Name'
cov.off('Cov-Name');

To unsubscribe one specific listener from a Covenant:

You'll need to save the token returned by your call to cov.on() or you can pass the same function to cov.off that you passed to the cov.on function.

Unsubscribe using token

var firstListener = cov.on('Cov-Name', function() {
	console.log('First Listener has fired!');
});

var secondListener = cov.on('Cov-Name', function() {
	console.log('Second listener has fired!');
});

// Both First and Second Listeners will fire
cov.signal('Cov-Name');

// Unsubscribe just the first Listener
cov.off('Cov-Name', firstListener);

// Only Second Listener will fire
cov.signal('Cov-Name');

Unsubscribe using function reference

var callback = function() {
    console.log('First Listener has fired!');
};

// Subscribe callback
cov.on('Cov-Name', callback);

// Callback will fire
cov.signal('Cov-Name');

// Unsubscribe callback
cov.off('Cov-Name', callback);

// Callback will NOT fire
cov.signal('Cov-Name');