需要帮助将函数的输出作为输入表单的值

Question

所以我试图创建一个表单，将下一个星期五的日期作为值发送。 该值应采用“YYYY-MM-DD”形式

这是我到目前为止所拥有的：

<input type="hidden" name="next_charge_scheduled_at" id="s1" value="" />
<script type="text/javascript">
 var elem = document.getElementById("s1");
elem.value = function()
{
var d = new Date();

switch (d.getDay())
{
case 0: d.setDate(d.getDate() + 5);
break;

case 1: d.setDate(d.getDate() + 4);
break;

case 2: d.setDate(d.getDate() + 3);
break;

case 3: d.setDate(d.getDate() + 2);
break;

case 4: d.setDate(d.getDate() + 1);
break;

case 6: d.setDate(d.getDate() + 6);
break;
}

return d;

};
</script>

但是，就我所见，这将返回整个函数，而不是结果。

我究竟做错了什么？

Answer 1

你已经绑定了一个函数到elem.value。如果你想把函数的结果放到elem.value，这样做：

<input type="hidden" name="next_charge_scheduled_at" id="s1" value="" />
<script type="text/javascript">
 var elem = document.getElementById("s1");
    elem.value=getDate();

    function getDate()
    {
    var d = new Date();

    switch (d.getDay())
    {
    case 0: d.setDate(d.getDate() + 5);
    break;

    case 1: d.setDate(d.getDate() + 4);
    break;

    case 2: d.setDate(d.getDate() + 3);
    break;

    case 3: d.setDate(d.getDate() + 2);
    break;

    case 4: d.setDate(d.getDate() + 1);
    break;

    case 5: d.setDate(d.getDate() + 7);
    break;

    case 6: d.setDate(d.getDate() + 6);
    break;
    }

    return `${d.getFullYear()}-${(d.getMonth() + 1) }-${d.getDate()}`;

    };

Answer 2

您需要创建一个函数，只有当我们像calculateFriday()那样执行函数时，我们才会得到我们将设置到输入字段的值！

 var elem = document.getElementById("s1"); elem.value = calculateFriday(); function calculateFriday() { var d = new Date(); switch (d.getDay()) { case 0: d.setDate(d.getDate() + 5); break; case 1: d.setDate(d.getDate() + 4); break; case 2: d.setDate(d.getDate() + 3); break; case 3: d.setDate(d.getDate() + 2); break; case 4: d.setDate(d.getDate() + 1); break; case 5: d.setDate(d.getDate() + 7); break; case 6: d.setDate(d.getDate() + 6); break; } return moment(d).format('YYYY-MM-DD');; }

 <script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.24.0/moment.min.js"></script> <input type="text" tname="next_charge_scheduled_at" id="s1" value="" />