今天是今年的第几天

<script>
var date123 = new Date();
                        var datemonth = new Array(31,28,31,30,31,30,31,31,30,31,30,31);
                        var year= date123.getFullYear()//获取年份
                        var month= date123.getMonth()//获取月份
                        var day= date123.getDate()//获取天
                        var sum = 0;
                        for( i = 0 ; i <month; i++){
                                     sum+=datemonth[i];
                        }sum += day;
                        document.write("今天是"+year+"年"+(month+1)+"月"+day+"日，是今年的第"+sum +"天");
</script>

动态时钟

<script>
function date(){
                        var date123 = new Date();
                        var year= date123.getFullYear()//获取年份
                        var month= date123.getMonth()//获取月份
                        var day= date123.getDate()//获取天
                        var hours= date123.getHours()//获取小时
                        var minutes= date123.getMinutes()//获取分钟
                        var seconds= date123.getSeconds()//获取秒;
                        document.getElementById("time").innerHTML=year+"年"+month+1+"月"+day+"日"+hours+"时"+minutes+"分"+seconds+"秒";
                    }

                          date();
                        setInterval( date,1000)
</script>