function findLongestWord(str) {
  str = str.split(" ");
  var i;
  longest = str[0];
  for(i = 1; i < str.length; i++){
    if (longest.length < str[i].length) {
      longest = str[i];
    }
  }
  return longest.length;
}

findLongestWord('The quick brown fox jumped over the lazy dog');