我认为要解决这个问题，你可以做的是最初隐藏anchor tag，并根据验证过程的成功或失败动态触发它，如下所示：

Html：

<!-- Add a placeholder element for the statement -->
<div id="next-stage" style="display: none;">
  <a href="mainmenu.html">Move on to the next stage</a>
</div>

<!-- Add a button to trigger the password verification -->
<button onclick="checkPassword()">Submit</button>

**JavaScript：**在函数方面，假设你已经有了验证密码完整性的逻辑，你可以这样做：
**注意：**请记住，密码验证是我硬编码的，以测试下面代码段中的逻辑，您可能需要根据用例编写自己的逻辑。

function checkPassword() {
  // Perform the password verification
  var isPasswordValid =true // Your password verification logic here

  if (isPasswordValid) {
    // Show the next stage statement
    document.getElementById("next-stage").style.display = "block";
    window.alert("Password verification successful!");
  } else {
    window.alert("Password verification failed!");
  }
}

<!-- Add a placeholder element for the statement -->
<div id="next-stage" style="display: none;">
  <a href="mainmenu.html">Move on to the next stage</a>
</div>

<!-- Add a button to trigger the password verification -->
<button onclick="checkPassword()">Submit</button>

对不起，我不太明白这个问题。
也许你正在寻找这样的东西。

$(document).ready(function(){
    $('#btn').attr('disabled',true);
    $('#rpw').keyup(function(){
        if($(this).val().length !=0)
          $('#btn').attr('disabled', false);            
        else
          $('#btn').attr('disabled',true);
    })
    $("#btn").click(function(){
      $("#pw").val() == $("#rpw").val() ?
      (window.alert('Successful!'), 
      $("#moveToNext").css("display", "block"))
      : (window.alert('Password not match!'),
      $("#moveToNext").css("display", "none"))
  });
});

<script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>

<label>Password: </label><input id="pw" type="password">
<br>
<label>Re-type Password: </label><input id="rpw" type="password">
<br>
<button id="btn">Check</button>
<div style="display:none;" id="moveToNext">
  <a href="mainmenu.html" onClick="checkPassword()">Move on the next stage</a>
</div>