http://www.freecodecamp.com/bskydive 's solution for Bonfire: Truncate a string

bonfire-truncate-a-string#.js

// Bonfire: Truncate a string
// Author: @bskydive
// Challenge: http://www.freecodecamp.com/challenges/bonfire-truncate-a-string#
// Learn to Code at Free Code Camp (www.freecodecamp.com)

function truncate(str, num) {
  
  return num>=str.length?str:str.substr(0,num-(num>=3?3:0))+'...';
}

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