JSFiddle - React, Tailwind, and code Playground

JavaScript

function LongestWord(sen) { 
  var count = '';
  var max = '';
//loops thru string & tallies letters in sequences
  for (i = 0; i < sen.length; i++) {   
    if ((sen.charAt(i) >= 'A' && sen.charAt(i) <= 'Z') || 
        (sen.charAt(i) >= 'a' && sen.charAt(i) <= 'z')) {
            count += sen.charAt(i);
//conditional tracks longest letter string to date
            if (count.length > max.length){
                max = count;             
                } 
    }
//resets count if it encounters a non letter value in string
    else {
        count = '';
         }
    }
  return max; 
}
alert(LongestWord("fun&!! time"));