html

<form class="form">
  <dl>
    <div>
      <dt>
        <label for="name">氏名</label>
      </dt>
      <dd>
        <input id="name" type="text" name="name" />
      </dd>
    </div>
    <div>
      <dt>
        <label for="mail">メールアドレス</label>
      </dt>
      <dd>
        <input id="mail" type="email" name="mail" />
      </dd>
    </div>
    <div>
      <dt>
        <label for="date">希望日時</label>
      </dt>
      <dd>
        <input id="date" type="date" name="date" />
      </dd>
    </div>
  </dl>
  <button type="submit">送信する</button>
</form>

js

const formElement = document.querySelector(".form");

const handleSubmit = function (event) {
  event.preventDefault();
  const submitedAllData = new FormData(event.target);
  const submitedData = {
    name: submitedAllData.get("name"),
    email: submitedAllData.get("mail"),
    date: submitedAllData.get("date"),
  };
  console.log(submitedData);
  event.target.reset();
};

formElement.addEventListener("submit", handleSubmit);