functional.js

// 06_Functional 

var doubler = function(n) {
  return n * 2;
};

var map = function (array, iteratorFunc) {
  var returnArray = [], val;
  for (var i = 0; i < array.length; i++) {
    val = iteratorFunc(array[i]);
    returnArray.push(val);
  }
  return returnArray;
};

var filter = function(array, filterFunc) {
  var returnArray = [];

  for (var i = 0; i < array.length; i++) {
    if (filterFunc(array[i])) {
      returnArray.push(array[i]);
    }
  }

  return returnArray;
};

var contains = function(collection, searchVal) {
  for (key in collection) {
    if (collection.hasOwnProperty(key)) {
      if (collection[key] === searchVal) {
        return true;
      }
    }
  }

  return false;
};

var countWords = function(sentence) {
  return sentence.split(" ").length;
};

var countWordsInReduce = function (currentVal, sentence) {
  return currentVal + countWords(sentence);
};

var reduce = function (array, startVal, combinerFunc) {
  var currentVal = startVal;
  for (var i = 0; i < array.length; i++) {
    currentVal = combinerFunc(currentVal, array[i]);
  }
  return currentVal;
};

/* Recursive solution, not required but just FYI */
var reduce_recursive = function (array, startVal, combinerFunc) {
  if (array.length === 0) {
    return startVal;
  }
  var nextStartVal = combinerFunc(startVal, array.shift());
  return reduce_recursive(array, nextStartVal, combinerFunc);
};


var sum = function (array) {
  var adder = function(currentSum, nextVal) {
    return currentSum + nextVal;
  };

  return reduce(array, 0, adder);
};

var every = function(array, checkerFunc) {
  var everyIterator = function (currentVal, nextVal) {
    return currentVal && checkerFunc(nextVal);
  };

  return reduce(array, true, everyIterator);
};

var any = function(array, checkerFunc) {
  var anyIterator = function (currentVal, nextVal) {
    return currentVal || checkerFunc(nextVal);
  };

  return reduce(array, false, anyIterator);
};