function task6() {
  function checkSpam(str) {
    str = str.toLowerCase();
    var spam = ['sex', 'spam'];

    for(var i = 0; i < spam.length; i++) {
      return !!~str.indexOf(spam[i]);
    }
  }

  console.log(checkSpam('get new Sex videos')); //true
  console.log(checkSpam('[SPAM] How to earn fast money?')); //true
  console.log(checkSpam('New PSD template')); //false
}