Javascript iterators suck so...
const it = Iter.fromArray(['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l'])
.enumerate()
.map(([k, v]) => [k, v.toUpperCase()])
.filter(([k, v]) => k % 2 == 0)
.map(([, v]) => v)
const collected = it.take(3)
.intoArray(); // -> [ 'A', 'C', 'E']
const collected2 = it
.intoArray(); // -> ['G', 'I', 'K']