robustTake.js

function take(n,xs){
  let it = typeof xs.next === 'undefined' ? makeIterator(xs) : xs
  let taken = []
  let nxt
  while(n > 0){
    if((nxt = it.next()).done)
      return taken
    taken.push(nxt.value)
    n--
  }
  return taken
}
function makeIterator(array) {
    let nextIndex = 0;
    return {
       next: function() {
           return nextIndex < array.length ?
               {value: array[nextIndex++], done: false} :
               {done: true};
       }
    };
}