<form id="myForm">
  <input type="text" id="myInput" required>
  <input type="submit" value="Submit">
</form>

document.getElementById("myForm").addEventListener("submit", function(event) {
  var input = document.getElementById("myInput");
  if (input.value === "") {
    alert("请填写文本框");
    event.preventDefault(); // 阻止表单提交
  }
});

document.getElementById("myForm").addEventListener("submit", function(event) {
  var input = document.getElementById("myInput");
  if (input.value === "") {
    alert("请填写文本框");
    event.preventDefault(); // 阻止表单提交
  } else {
    window.location.href = "另一个页面的URL";
  }
});