<script>

  //封装时间格式

  function format(time, format) {

    var t = new Date(time);

    var tf = function (i) {

      return (i < 10 ? '0' : '') + i

    };

    return format.replace(/yyyy|MM|dd|HH|mm|ss/g, function (a) {

      switch (a) {

        case 'yyyy':

          return tf(t.getFullYear());

          break;

        case 'MM':

          return tf(t.getMonth() + 1);

          break;

        case 'mm':

          return tf(t.getMinutes());

          break;

        case 'dd':

          return tf(t.getDate());

          break;

        case 'HH':

          return tf(t.getHours());

          break;

        case 'ss':

          return tf(t.getSeconds());

          break;

      }

    })

  }

</script>

 //引用

           var getDate1=new Date();

           console.log(getDate1);    //输出Mon Oct 30 2017 14:33:20 GMT+0800 (中国标准时间)

          var result1=format(getDate1,'yyyy-MM-dd');

           console.log(result1);            //输出2017-10-30

           var getDate2=new Date().toLocaleDateString();

           console.log(getDate2);    //输出2017/10/30

           var result2=format(getDate2,'yyyy-MM-dd');

           console.log(result2);            //输出2017-10-30