createRandomString()

createRandomString.js

function createRandomString(minLen, maxLen) {
  var alphabet = 'abcdefghijklmnopqrstuvwxyz'.split(''),
      stringLen = Math.floor(Math.random() * (maxLen - minLen + 1)) + minLen,
      string = '';

  for(var i = 0; i < stringLen; i++) {
    string += alphabet[Math.floor(Math.random() * alphabet.length)];
  }
  return string;
}