Generic random alphabetical strings with JavaScript

genRandomStrings.js

var validChars = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz'.split('');
var validCharsUpperBound = validChars.length - 1;

function randomInt(lower, upper) {
  return lower + Math.floor(Math.random() * (upper - lower + 1))
}

function randomLetter() {
  return validChars[randomInt(0, validCharsUpperBound)];
}

function randomString() {
  var randomLength = randomInt(0, 32);
  var randomLetters = [];
  for (var r = 0; r <= randomLength; r++) {
    randomLetters.push(randomLetter());
  }
  return randomLetters.join('');
}

var stringsToTest = [];
for (var s = 0; s < 100; s++) {
  stringsToTest.push(randomString());
}

// Add duplicates?
for (var d = 0; d < 5; d++) {
  var duplicateIndex = randomInt(0, stringsToTest.length - 1);
  stringsToTest.push(stringsToTest[duplicateIndex]);
}


console.log(JSON.stringify(stringsToTest, null, 2));