为什么我代码里面写的attime= time.getHours()+":"+time.getMinutes()+":"+time.getSeconds()+":";输出来是点分秒啊？

<script type="text/javascript">

  var attime;

  function clock(){

    var time=new Date();          

    attime= time.getHours()+":"+time.getMinutes()+":"+time.getSeconds()+":";

    document.getElementById("clock").value = attime;

    var int=setInterval(clock, 1000);

  }

</script>