<form id="myForm">
  <label for="name">姓名：</label>
  <input type="text" id="name" name="name"><br><br>
  
  <label for="email">邮箱：</label>
  <input type="email" id="email" name="email"><br><br>
  
  <label for="message">留言：</label>
  <textarea id="message" name="message"></textarea><br><br>
  
  <input type="submit" value="提交">
</form>

document.getElementById("myForm").addEventListener("submit", function(event) {
  event.preventDefault(); // 阻止表单默认提交行为
  
  var name = document.getElementById("name").value;
  var email = document.getElementById("email").value;
  var message = document.getElementById("message").value;
  
  var listItem = document.createElement("li");
  listItem.textContent = "姓名：" + name + "，邮箱：" + email + "，留言：" + message;
  
  var list = document.getElementById("myList");
  list.appendChild(listItem);
  
  // 清空表单
  document.getElementById("name").value = "";
  document.getElementById("email").value = "";
  document.getElementById("message").value = "";
});

<ul id="myList"></ul>