09_truncated_string.js

function truncateString(str, num) {
  if (str.length <= num) {
    return str;
  } else if (num <= 3) {
    return str.slice(0, num) + "...";
  } else {
    return str.slice(0, (num - 3)) + "...";
  }
}

console.log(truncateString("A-tisket a-tasket A green and yellow basket", 11));