js实现本地时间同步功能

//时间
function getTime(){
 var ndate = new Date();
 var nyear = ndate.getFullYear();
 var nmOnth= ndate.getMonth()+1;
 var nday = ndate.getDate(); 
 var nhour = ndate.getHours();
 var nminute = ndate.getMinutes();
 var nsecOnd= ndate.getSeconds();
 // 如果分钟或小时的值小于10，则在其值前加0，比如如果时间是下午3点20分9秒的话，则显示15：20：09
 nmOnth=checkTime(nmonth);
 nday=checkTime(nday);
 nminute=checkTime(nminute); 
 nsecOnd=checkTime(nsecond); 
 document.getElementById('nowDateTimeSpan').innerHTML=nyear+"-"+nmonth+"-"+nday+" "+nhour+":"+nminute+":"+nsecond;
 document.getElementById('nowDateTimeSpan1').innerHTML=nyear+"-"+nmonth+"-"+nday+" "+nhour+":"+nminute+":"+nsecond;
 document.getElementById('nowDateTimeSpan2').innerHTML=nyear+"-"+nmonth+"-"+nday+" "+nhour+":"+nminute+":"+nsecond;
 document.getElementById('nowDateTimeSpan3').innerHTML=nyear+"-"+nmonth+"-"+nday+" "+nhour+":"+nminute+":"+nsecond;
 document.getElementById('nowDateTimeSpan4').innerHTML=nyear+"-"+nmonth+"-"+nday+" "+nhour+":"+nminute+":"+nsecond; 
 //setTimeout('getTime()',1000);//每一秒中重新加载startTime()方法
 function checkTime(i){ 
  if (i<10){
   i="0" + i;
  } 
  return i;
 }
}