Shouter NPM | npm.io

Shouter

Simple, yet powerful micro framework for event broadcasts.

import { shouter } from 'shouter';

const help = () => alert('HELP!');
shouter.on('avalanche', '*', help);
shouter.trigger('avalanche', 'danger');
shouter.off('avalanche', help);

Install

NPM:

$ npm install shouter

And then (ES5):

var shouter = require('shouter').shouter;

shouter
    .on('questions', 'life', function(q) {
        if (q === 'meaning') {
            return 42;
        } else {
            return 44;
        }
    });

shouter
    .trigger('questions', 'life', 'meaning')
    .results
    .then(function(questions) {
        questions.forEach(function(answer) {
            console.log(answer); // 42
        })
    });

See example folder for ES6 and ES.next example.

Size

≈816 byte (gzipped)

Listening to channels and routes

When subscribing to an event you must specify a channel, route and a callback:

shouter.on('channel', 'route', callback);

The route can however be a asterisk, *, to subscribe on all routes on the specific channel:

shouter.on('channel', '*', callback);
shouter.trigger('channel', 'route'); // this will trigger "callback".

You can also choose to trigger all routes:

shouter.on('channel', 'route', callback);
shouter.trigger('channel', '*'); // this will trigger "callback".

You can also bind a context to the callback:

let context = {called: 0};
let fun = function() {
    this.called++;
}
shouter.on('channel', 'route', fun, context);
// Same as: shouter.on('channel', 'route', callback.bind(context));

You can also pass a number of arguments:

let fun = (a, b, c) => a+b+c;
shouter.on('channel', 'route', fun);
shouter.trigger('channel', 'route', 1, 2, 3);

Or something like this:

shouter.on('math', 'min', Math.min);
shouter
    .trigger('math', 'min', 1, 2, 3)
    .results
    .then(result => console.log(result)); // 1

Async

All events will be trigged as async events:

let callback = () => console.log('callback');
shouter.on('channel', 'route', callback);
shouter.trigger('channel', 'route');
console.log('last one');

// Output:
// last one
// callback

trigger will however return a promise object with the result of all trigged events:

let callback = () => console.log('callback');
shouter.on('channel', 'route', callback);
shouter
    .trigger('channel', 'route')
    .results
    .then(() => console.log('last one'));

// This will output:
// callback
// last one

results will contain the result of all trigged events:

let pi = () => 3.142;
let e = () => 2.718;
shouter.on('calc', 'pi', pi);
shouter.on('calc', 'e', e);
shouter
    .trigger('calc', '*')
    .results
    .then(calc => {
        calc.forEach(result => console.log(result));
    });

// This will output (or in reverse order):
// 3.142
// 2.718

results is wrapped in Promise.all:

let pi = () => throw new Error('I forgot pi');
let e = () => 2.718;
shouter.on('calc', 'pi', pi);
shouter.on('calc', 'e', e);
shouter
    .trigger('calc', '*')
    .results
    .then(calc => {
        calc.forEach(result => console.log(result));
    })
    .catch(error => {
        console.log(error);
    });

// This will output:
// I forgot pi

You can save an event if you don't know if the subscriber has started yet:

shouter
    .trigger('channel', 'route')
    .save(); // Save the event to future subscriber

let callback = () => console.log('callback');
let context = undefined; // default: undefined
let getAlreadySubmittedEvents = true; // default: false
shouter.on('channel', 'route', callback, context, getAlreadySubmittedEvents); // will trigger callback

Decorators

If you are using ES2017 (aka ES8) (or typescript) you can decorate your classes: You can run this example by babel-node examples/decorators.js (remember to run npm install first)

import {shouter, triggerOnEvent, shoutOnSet, shoutOnGet} from 'shouter';

class Person {

    @shoutOnSet('name', 'changing')
    set name(name) {
        return (this._name = name);
    }

    @shoutOnGet('name', 'asking')
    get name() {
        return this._name;
    }

    // This will only work on static methods since we don't have access to `this`
    // See: https://github.com/wycats/javascript-decorators/issues/13#issuecomment-120875498 for more information
    @triggerOnEvent('speak', 'greetings')
    sayHi(name) {
        console.log(`Hello, ${name}`);
    }

}

shouter.on('name', 'changing', newName => console.log(`My new name is ${newName}`));
shouter.on('name', 'asking', name => console.log(`Someone is asking for my name and I told them: ${name}`));

let oskar = new Person();
oskar.name = 'Oskar';
console.log(`The person's name is: ${oskar.name}`);

shouter.trigger('speak', 'greetings', 'Dexter Morgan');

// output:
// The person's name is: Oskar
// My new name is Oskar
// Someone is asking for my name and I told them: Oskar
// Hello, Dexter Morgan