javascript - 提示文本框是否为空

我的表格：

<form method="post" action="getQuote.php" onsubmit="check()">
    <table>
        <tr>
            <td>Name:</td>
            <td>
                <input id="idname" class="inputBox" name="name"/>
            </td>
        </tr>
        <tr>
            <td>Phone Number:</td>
            <td>
                <input id="idphone" class="inputBox" name="phone" />
            </td>
        </tr>
        <tr>
            <td>Moving From:</td>
            <td>
                <input id="idfrom" class="inputBox" name="from" />
            </td>
        </tr>
        <tr>
            <td>Moving To:</td>
            <td>
                <input id="idto" class="inputBox" name="to" />
            </td>
        </tr>
        <tr>
            <td>Date:</td>
            <td>
                <input id="iddate" class="inputBox" name="date" />
            </td>
        </tr>
        <tr>
            <td>&nbsp;</td>
            <td> &nbsp; </td>
        </tr>
        <tr>
            <td></td>
            <td>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
                <button name="signup" class="myButton">
                <font style="color: #ffffff">Get A Quote</font>
                </button>
            </td>
        </tr>
    </table>
</form>

我的脚本：

<script>
    function check() {
        var n = document.getElementById(idname);
        var p = document.getElementById(idphone);
        var f = document.getElementById(idfrom);
        var t = document.getElementById(idto);
        var d = document.getElementById(iddate);
        var test1 = n.length;
        var test2 = p.length;
        var test3 = f.length;
        var test4 = t.length;
        var test5 = d.length;
        alert(test1);
        alert(test2);
        alert(test3);
        alert(test4);
        alert(test5);
    }
</script>

我将脚本称为表单的onsubmit函数，但页面未显示警告。相反，它将转到getQuote.php文件。谁能告诉我，这是什么问题？我认为，我缺少一些愚蠢的东西。

N.B：无论值是否为空，我都没有编写要比较的部分。只是检查值。

提前致谢。

最佳答案

尝试一下

   <script>
        function check() {
            var n = document.getElementById('idname');
            var p = document.getElementById('idphone');
            var f = document.getElementById('idfrom');
            var t = document.getElementById('idto');
            var d = document.getElementById('iddate');
            var test1 = n.length;
            var test2 = p.length;
            var test3 = f.length;
            var test4 = t.length;
            var test5 = d.length;
            alert(test1);
            alert(test2);
            alert(test3);
            alert(test4);
            alert(test5);

        }
    </script>