function wordify(string) {
  var index = 0;
  var word  = '';
  var words = [];
  var end   = string.length - 1;

  while(string[index] !== undefined) {
    word += /^\s/.test(string[index]) ? '' : string[index];

    if (/\s/.test(string[index]) || index === end) {
      words.push(word);
      word = '';
    }

    index++;
  }

  return words;
}

function reverse_words(words) {
  return words.map(function(word){
    var end   = word.length - 1;
    var rword = '';

    for (i = end; i >= 0; --i) {
      rword += word[i];
    }

    return rword;
  });
}

var text  = 'Sorry but my dog ate my homework';
console.log(text);

var words = wordify(text);
//console.log(words);

var rwords = reverse_words(words);
//console.log(rwords);

var rtext  = rwords.join(' ');
console.log(rtext);