JavaScript OnBlur事件阻止提交HTML表单

<form onsubmit="return validateForm()">
 <label for="email">Email:</label>
 <input type="email" id="email" name="email" onblur="validateEmail()">
 <input type="submit" value="Submit">
</form><script>
function validateEmail() {
  var emailInput = document.getElementById("email");
  var email = emailInput.value;
  var re = /\S+@\S+\.\S+/;
  if (re.test(email)) {
    emailInput.style.borderColor = "";
  } else {
    emailInput.style.borderColor = "red";
  }
}

function validateForm() {
  var emailInput = document.getElementById("email");
  if (emailInput.style.borderColor == "red") {
    alert("Please enter a valid email address");
    return false;
  }
  return true;
}
</script>