如何验证我的输入字段以请求输入一些文本？

<form>
  <label for="name">姓名：</label>
  <input type="text" id="name" name="name" required><br><br>

  <label for="email">电子邮件：</label>
  <input type="email" id="email" name="email" required><br><br>

  <label for="password">密码：</label>
  <input type="password" id="password" name="password" pattern=".{8,}" title="至少8个字符"><br><br>

  <input type="submit" value="提交">
</form>

document.querySelector('form').addEventListener('submit', function(event) {
  var name = document.getElementById('name').value;
  var email = document.getElementById('email').value;
  var password = document.getElementById('password').value;

  if (name === '' || email === '' || password === '') {
    alert('所有字段都必须填写');
    event.preventDefault();
  }

  if (password.length < 8) {
    alert('密码至少需要8个字符');
    event.preventDefault();
  }
});