用JS弹出“有输入框并带有是、否、…

<script type="text/javascript">
function diag()
{
    var str=prompt("随便写点儿啥吧","比如我叫啥");
    if(str)
    {
        alert("您刚输入的是："+ str)
    }
}

</script>
<p>
<input type="submit" value="Sumit" name="Su1" onclick="diag()" />
</p>