eager timerObservable

timerObservable.eager.js

function timer(delay){
    const subscribers = []
    let count = 0
    const interval = setInterval(() => {
        subscribers.forEach(observer => observer.next(count))        
        count++;
    }, delay)

    const timerObservable = {
        subscribe: observer => {
            subscribers.push(observer)
            return {
                unsubscribe: () => subscribers.splice(subscribers.indexOf(observer), 1)
            }
        }
    }

    return timerObservable
}

const interval = timer(1000)
const sub1 = interval.subscribe({
    next: (val) => console.log("sub1", val)
})
setTimeout(() => {
    const sub2 = interval.subscribe({
        next: (val) => console.log("sub2", val)
    })
}, 1500)
setTimeout(() => {
    sub1.unsubscribe()
}, 3500)