把下面的代码修改成可以获取单个id的input type=text id=websiteId placeholder=请输入网站IDinput type=button class=btn value=下载单个id onClick=windowlocationhref=webpicphpact=downid&type=part; downloadid if $action == downid

<input type="text" id="websiteId" placeholder="请输入网站ID">
<input type="button" class="btn" value="下载单个id" onClick="downloadSingleId()">
<script>
function downloadSingleId() {
    var websiteId = document.getElementById("websiteId").value;
    window.location.href = 'webpic.php?act=downid&type=part&id=' + websiteId;
}
</script>