callbackLesson.js

var arr = [1,2,3,4,5,6,7,8];

var lookArr = function(array, callback) {
  var i = 0,
      len = array.length;

  if (typeof callback !== 'function') {
    callback = false;
  }

  for(; i < len; i += 1) {
    if(array[i] % 2 === 0) {
      
      console.log(array[i] + ' is even.');
      if(callback) {
        callback(array[i]);
      }
    }
  }
}

var divideElement = function(element) {
  return element / 2;
}