Observable.js

class Observable {

	constructor(){

		this.observers = []

	}

	add(callback){

		if( typeof callback === 'function' )
			this.observers.push({

				callback: callback

			})

		return this

	}

	remove(callback){

		let index = this.observers.findIndex( observer => observer.callback == callback )

		if(~index) return this.observers.splice(index, 1)

		return []

	}

	notify(data){

		this.observers.forEach( observer => observer.callback(data) )

		return this

	}

	clear(){

		this.observers = [];

		return this

	}

}