Andrew entered canSubmit() in the console and got FALSE, I always get TRUE even though our codes match perfectly.

//Prob: Hints are shown even when form is valid
//Solution: Hide/Show hints when form is valid/invalid
var $password = $("#password");
var $confirmPassword = $("#confirm_password");

//Hide hints
$("form span").hide();

function isPasswordValid() {
  return $password.val().length > 8;
}

function arePasswordsMatching() {
  return $password.val() === $confirmPassword.val();
}

//Checks to see if password is valid if so, enable submit
function canSubmit() {
  return isPasswordValid && arePasswordsMatching();
}

function passwordEvent() {
  //Find out if password is valid
  if(isPasswordValid()) {
    //Hide hint if valid
    $password.next().hide();
  } else {
    //else show hint
    $password.next().show();
  }
}

function confirmPasswordEvent() {
  //Find out if password and confirmation match
  if(arePasswordsMatching()) {
    //Hide hint if match
    $confirmPassword.next().hide();
  } else {
    //else show hint
    $confirmPassword.next().show();
  }
}

function enableSubmitEvent() {
  $("#submit").prop("disabled", !canSubmit());
}

//when event happens on password input
$password.focus(passwordEvent).keyup(passwordEvent).keyup(confirmPasswordEvent).keyup(enableSubmitEvent);

//when event happens on confirmation input
$confirmPassword.focus(confirmPasswordEvent).keyup(confirmPasswordEvent).keyup(enableSubmitEvent);

enableSubmitEvent();