function counter() {

	var date = new Date();

	var year = date.getFullYear();

	var date2 = new Date(year, 12, 31, 23, 59, 59);

	/*转换成秒*/
	var time = (date2 - date) / 1000;

	var day = Math.floor(time / (24 * 60 * 60))


	var hour = Math.floor(time % (24 * 60 * 60) / (60 * 60))

	var minute = Math.floor(time % (24 * 60 * 60) % (60 * 60) / 60);

	var second = Math.floor(time % (24 * 60 * 60) % (60 * 60) % 60);

	var str = year + "年还剩" + day + "天" + hour + "时" + minute + "分" + second + "秒";

	console.log(str);

}

window.setInterval("counter()", 1000);

javascript 网页中实现一个计算当年还剩多少时间的倒数计时程序