const array$ = of(1,2,3,4,5,6,7,8,9,10);

// Map transforms data in this case evaluates every entry and tranforms it into a boolean

const evensMap = array$.pipe(
    map(number => number % 2 == 0)
    );
evensMap.subscribe(x => console.log(x));

// Output:
// false
//  true
//  false
//  true
//  false
//  true
//  false
//  true
//  false
//  true

// Filter evaluates every entry but only return that entry if pass the predicate function otherwise ignore that entry.

const evensFilter = array$.pipe(
    filter(number => number % 2 == 0)
    );
evensFilter.subscribe(x => console.log(x));

// Output:
//  4
//  6
//  8
//  10