Fun with generators

generator.js

function* gen(param) {
  if (!Array.isArray(param)) 
    yield param;
  else
    for (let item of param)
      yield* gen(item);
}

function* genNumbers(iterable) {
  var items = gen(iterable);
  for (let item of items)
    if ( typeof item === 'number' && !isNaN(item))
      yield item;
}

function* genEvenNumbers(iterable) {
  var numbers = genNumbers(iterable);
  for (let num of numbers)
    if (num % 2 === 0)
      yield num;
}
function* genOddNumbers(iterable) {
  var numbers = genNumbers(iterable);
  for (let num of numbers)
    if (num % 2 !== 0)
      yield num;
}

function genGenerator(assert) {
  return function* generator(iterable) {
    var items = gen(iterable);
   
    for (let item of items)
      if (assert(item))
        yield item;
  }
}



function sumArray(arr) {
  let sum = 0;
  const numbersIterator = genNumbers(arr);
  for (let number of numbersIterator)
    sum += number;
  
  return sum;
}

function averageArray(arr) {
  return sumArray(arr) / arr.length;
}

function test() {
  var arr = [1,2,3,'done', 4,5, [6,7],[8,[9,[10]],'hello']];
  var numbersIterator = genNumbers(arr);

  for (let number of numbersIterator) {
    console.log(number);
  }
  var genLessThen8 = genGenerator(item => item < 8);
  for (let number of genLessThen8(arr)) {
    console.log(number);
  }  
}