我有一個php文件，該文件可檢索以html形式輸入的信息并將其保存到mysql數據庫中。我面臨的問題是我無法弄清楚如何阻止頁面重定向到insertinfo.php。我希望用戶停留在同一index.html頁面上，在表單提交時將出現模式。以下是我的index.html和insertinfo.phpindex.html文件：<div class="form ">      <form class="container" action="insertinfo.php">         <input type="text" id="firstname" class="form_input" placeholder="First Name" name="firstname" required>        <input type="text" id="lastname" class="form_input" placeholder="Last Name" name="lastname" required>        <input type="text" id="email" class="form_input" placeholder="Email Address" name="email" required>        <input type="submit" id="myBtn" class="submit" value="Download eBook">      </form></div><div id="myModal" class="modal">    <!-- Modal content -->    <div class="modal-content">      <div class="modal-header">        <div class="icon-box">          <i class="material-icons">check</i>        </div>      </div>      <div class="modal-body">        <h4>An email with a download link towards the eBook has been sent to you.</h4>        <p>Please check your inbox and your spam/bulk messages.</p>        <a href="">Continue</a>      </div>    </div>  </div><script type="text/javascript">   var modal = document.getElementById("myModal");   // Get the button that opens the modal   var btn = document.getElementById("myBtn");   // When the user clicks the button, open the modal    btn.onclick = function(event) {      var fnameInput = document.getElementById("firstname").value;      var lnameInput = document.getElementById("lastname").value;      var emailInput = document.getElementById("email").value;      if(fnameInput.length == 0 || lnameInput.length == 0 || emailInput.length == 0){          event.preventDefault();          alert("You must complete all existing fields");      } else {          modal.style.display = "block";      }   }</script>