JavaScript表单校验生效时提交按钮失效，如何实现日期大小校验

一、现有代码错误点 #

• 校验函数返回逻辑错误：所有字段校验通过后，函数最终返回return false，而onsubmit事件接收到false返回值会直接阻止表单默认提交行为，这是校验通过后点击提交无响应的核心原因。
• 日期输入框ID存在冗余空格：到达日期、离开日期输入框的ID属性末尾多写了空格（id="arrival "、id="departure "），如果后续通过ID获取元素会匹配失败。
• 单选框label关联错误：信用卡选项的label的for属性值为Credit，对应单选框的ID为cred，二者不匹配，点击label无法选中对应单选框。

二、修复实现（含到达日期早于离开日期校验逻辑） #

以下是修复后完整的代码，调整了校验返回逻辑，补充了日期校验规则，修正了上述错误：

<!DOCTYPE html>
<head>
    <title>Book Accomodations</title>
    <link rel="stylesheet" href="style.css">

    <script>
      function validate(){  
        var x = document.forms["myform"]["fname"].value;
        var y = document.forms["myform"]["lname"].value;
        var email = document.forms["myform"]["email"].value;
        var arrivalVal = document.forms["myform"]["adate"].value;
        var departureVal = document.forms["myform"]["ddate"].value;
        var filter = /^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$/;
        var getSelectedValue = document.querySelector('input[name="payment"]:checked');  

        if (x == "" || x == null) {
          alert("First Name must be filled out");
          return false;
        } else if (y == "" || y == null) {
          alert("Last Name must be filled out");
          return false;
        } else if (!email.match(filter)) {
          alert("Enter Proper Email ID");
          return false;
        } else if(document.getElementById("country").value == "") {
          alert("Please select a country"); 
          return false;
        } else if(getSelectedValue == null) {   
          alert("Select Payment Mode");
          return false;
        } else if(!arrivalVal || !departureVal) {
          alert("Please select arrival and departure date");
          return false;
        }
        // 日期校验逻辑
        const arrivalDate = new Date(arrivalVal);
        const departureDate = new Date(departureVal);
        if(arrivalDate >= departureDate){
          alert("Arrival date must be earlier than departure date");
          return false;
        }
        // 所有校验通过，返回true允许提交
        return true;
      } 
    </script>  
</head>
<body>
    <div class="form">
    <form name ="myform" action="function.php" onsubmit="return validate();" id="form" method="POST">
        <label for="fname">First Name:</label>
        <input type="text" id="fname" name="fname" /><br>
        <label for="lname">Last Name:</label>
        <input type="text" id="lname" name="lname" /><br>
        <label for="email">Email:</label>
        <input type="email" id="email" name="email" /><br>
        <label for="arrival">Arrival Date:</label>
        <!-- 修正ID多余空格 -->
        <input type="date" id="arrival" name="adate" ><br>
        <label for="departure">Departure Date:</label>
        <!-- 修正ID多余空格 -->
        <input type="date" id="departure" name="ddate" /><br>

        <label for="country">Choose a Country:</label>
        <select id="country" name="country" form="myform">
          <option disabled selected value> -- select an option -- </option>
          <option value="India">India</option>
          <option value="U.S.A.">U.S.A.</option>
          <option value="Nepal">Nepal</option>
          <option value="Bangladesh">Bangladesh</option>
          <option value="Germany">Germany</option>
          <option value="Spain">Spain</option>
          <option value="Italy">Italy</option>
          <option value="Sri Lanka">Sri Lanka</option>
          <option value="China">China</option>
        </select>
        <p>Payment Mode:</p>
        <input type="radio" id="deb" name="payment" value="Debit" />
        <label for="deb">Debit Card</label>
        <input type="radio" id="cred" name="payment" value="Credit"/>
        <!-- 修正for属性值和单选框ID匹配 -->
        <label for="cred">Credit Card</label>
        <br>
        <input type="submit" id="submit" name="submit" value="submit" style="width: 100px;"/>
        <input type="reset" value="Reset" style="width: 100px; "/>
    </form>
    </div>
</body>

内容的提问来源于stack exchange，提问作者shubham2708