Coderbyte Longest Word in a string

3-LongestWord.js

function LongestWord(sen) { 
  longest = "";
  // code goes here
  var words = sen.split(" ");
  for(i = 0; i < words.length; i++) {
    if(words[i].length > longest.length) {
      longest = words[i];
    } 
  }
  return longest;
}
   
// keep this function call here 
// to see how to enter arguments in JavaScript scroll down
LongestWord(readline()); 

Fails edge cases (e.g. "a confusing /:sentence:/[ this is not!!!!!!!~")