禁用提交按钮，直到使用JavaScript填充了必填字段

<input type="text" name="name" required>

// 获取表单元素
var form = document.getElementById("myForm");

// 获取必填字段元素
var requiredFields = form.querySelectorAll("[required]");

// 检查必填字段是否已填写
function checkRequiredFields() {
  for (var i = 0; i < requiredFields.length; i++) {
    if (requiredFields[i].value === "") {
      return false;
    }
  }
  return true;
}

// 监听表单元素的输入事件
form.addEventListener("input", function() {
  var submitButton = document.getElementById("submitButton");
  submitButton.disabled = !checkRequiredFields();
});

#submitButton:disabled {
  background-color: gray;
  cursor: not-allowed;
}