在表单中单击提交按钮后，如何打开特定的网页？

<form action="https://example.com/target-page.html" method="post">
  <!-- 表单字段 -->
  <input type="text" name="username" placeholder="用户名">
  <input type="password" name="password" placeholder="密码">
  <!-- 提交按钮 -->
  <input type="submit" value="提交">
</form>

<form>
  <!-- 表单字段 -->
  <input type="text" name="username" placeholder="用户名">
  <input type="password" name="password" placeholder="密码">
  <!-- 提交按钮 -->
  <input type="submit" value="提交" onclick="openTargetPage()">
</form>

<script>
function openTargetPage() {
  // 获取表单数据
  var username = document.getElementsByName("username")[0].value;
  var password = document.getElementsByName("password")[0].value;
  
  // 构造目标网页的URL，包含表单数据作为参数
  var targetUrl = "https://example.com/target-page.html?username=" + username + "&password=" + password;
  
  // 打开目标网页
  window.location.href = targetUrl;
}
</script>