js时间日期和毫秒的相互转换

代码如下:
<script>
function c1(){
    var d = document.getElementsByName("s")[0].value;
    var b = (new Date(d)).getTime();
    document.getElementsByName("s")[0].value = b;   
}
function c2(){
    var d = document.getElementsByName("d")[0].value;
    var b = new Date(d);
    b.setTime(d);
    document.getElementsByName("d")[0].value = b;   
}
</script>
 转毫秒<input name="s" value=""><input type="button" onclick="c1()"

value="ssss" >
转日期<input name="d" value=""><input type="button"

onclick="c2()" value="dddd" >