Functional Programming in JavaScript - 6

gistfile1.js

var forEach = function (list, action) {
  for (var i = 0; i < list.length; i++) {
    action(list[i]);
  }
};

var reduce = function (combine, base, list) {
  forEach(list, function (item) {
    base = combine(base, item);
  });
  return base;
};

var countNegativeNumbers = function (negativeNumbersTillNow, currentNumber) {
  if (typeof currentNumber === "number" && currentNumber < 0) {
    negativeNumbersTillNow += 1;
  }
  return negativeNumbersTillNow;
};

var initialCount = 0;

console.log(reduce(countNegativeNumbers, initialCount, [1, -1, 0, 45, "-42", -42]));