locustjs-signals

This library implements publisher-subscribe pattern and provides utility classes in this topic.

Classes

SubscriptionManagerBase

This class is the abstraction of subscription managers.

class SubscriptionManagerBase {
	subscribe(event, eventHandler, config) { ... }
	dispatch(event, data) { ... }
	disable(subscription) { ... }
	enable(subscription) { ... }
	unsubscribe(subscription) { ... }
}

Methods:

Method	Description
subscribe	subscribes the given event handler for the specified event.
dispatch	trigger event, sending data to all subscriber of the given event
enable	enable subscriber
disable	disable subscriber
unsubscribe	unsubscribe the subscriber

SubscriptionManagerDefault

Default implementation of SubscriptionManagerBase. It uses an internal array to store subscribers, hence, the instance of this subscription manager should be used as a singleton object in order to perform correctly.

examples

example 1

const sm = new SubscriptionManagerDefault();

const s1 = sm.subscribe('todo_added', x => console.log(`todo added: ${JSON.stringify(x)}`));
const s2 = sm.subscribe('todo_updated', x => console.log(`todo updated: ${JSON.stringify(x)}`));
const s2 = sm.subscribe('todo_removed', x => console.log(`todo removed: ${JSON.stringify(x)}`));

sm.dispatch('todo_added', { id: 1, title: 'Checking emails', done: false });
sm.dispatch('todo_updated', { id: 1, done: true });
sm.dispatch('todo_removed', { id: 1 });

sm.unsubscribe(s1);
sm.unsubscribe(s2);
sm.unsubscribe(s3);

example 2

class TodoManager {
	constructor(subscriptionManager) {
		this._todos = [];
		this.sm = subscriptionManager;
	}
	add(todo) {
		this._todos.push(todo);
		sm.dispatch('todo_added', todo);
	}
	findIndex(todo) {
		return this._todos.findIndex(x => x.id === todo.id);
	}
	update(newTodo) {
		const index = this.findIndex(newTodo);
		
		if (index >= 0) {
			const oldTodo = this._todos[index];
			const updatedTodo = Object.assign({}, oldTodo, newTodo);
			this._todos.splice(index, 1, updatedTodo);
			
			sm.dispatch('todo_updated', newTodo);
			
			return true;
		}
		
		return false;
	}
	remove(todo) {
		const index = this.findIndex(todo);
		
		if (index >= 0) {
			this._todos.splice(index, 1);
			
			sm.dispatch('todo_removed', todo);
			
			return true;
		}
		
		return false;
	}
	getAll() {
		return this._todos;
	}
}

const sm = new SubscriptionManagerDefault();

const s1 = sm.subscribe('todo_added', x => console.log(`todo added: ${JSON.stringify(x)}`));
const s2 = sm.subscribe('todo_updated', x => console.log(`todo updated: ${JSON.stringify(x)}`));
const s2 = sm.subscribe('todo_removed', x => console.log(`todo removed: ${JSON.stringify(x)}`));

const tm = new TodoManager();

tm.add({ id: 1, title: 'Checking emails', done: false });
tm.update({ id: 1, done: true });
tm.remove{ id: 1 });

sm.unsubscribe(s1);
sm.unsubscribe(s2);
sm.unsubscribe(s3);