js 显示日期时间，时间过一秒加1

<div id="data"><font>2017年10月17日  15:11:11</font></span>

function showLocale(objD) {       

 var str, colorhead, colorfoot;       

 var yy = objD.getYear();       

 if (yy < 1900) yy = yy + 1900;        var MM = objD.getMonth() + 1;       

 if (MM < 10) MM = '0' + MM;        var dd = objD.getDate();       

 if (dd < 10) dd = '0' + dd;        var hh = objD.getHours();       

 if (hh < 10) hh = '0' + hh;        var mm = objD.getMinutes();       

 if (mm < 10) mm = '0' + mm;        var ss = objD.getSeconds();      

  if (ss < 10) ss = '0' + ss;        var ww = objD.getDay();       

 if (ww == 0) colorhead = "";        

if (ww > 0 && ww < 7) colorhead = "";

str = colorhead + yy + "年" + MM + "月" + dd + "日   " + hh + ":" + mm + ":" + ss + " ";

return (str);

}

function tick() {

var today;

today = new Date();

document.getElementById("new_data").innerHTML = showLocale(today);

window.setTimeout("tick()", 1000);

}

tick();