Truncate a string: Truncate a string (first argument) if it is longer than the given maximum string length (second argument). Return the truncated string with a "..." ending.

truncateStr.js

function truncate(str, num) {
  // Clear out that junk in your trunk
  return num >= str.length? str: str.slice(0, num - (num <= 3 ? 0 : 3)) + '...';
}

truncate("A-tisket a-tasket A green and yellow basket", 11);