SOURCE

function writeDocument(variable) {
    document.write(variable + "<br/>");
} 

writeDocument("定义时间对象--------------");
var oToday=new Date();

writeDocument("年:"+oToday.getFullYear());
writeDocument("月:"+oToday.getMonth());
writeDocument("日:"+oToday.getDate());
writeDocument("时:"+oToday.getHours());
writeDocument("分:"+oToday.getMinutes());
writeDocument("秒:"+oToday.getSeconds());
writeDocument("毫秒:"+oToday.getMilliseconds());

var weeks = ["星期日", "星期一", "星期二", "星期三", "星期四", "星期五", "星期六"];

writeDocument("今天是"+weeks[oToday.getDay()]);
writeDocument("设置年月日时分秒毫秒-------");

var oDate=new Date(2019);

oDate.setFullYear(2020);
writeDocument("年:"+oDate.getUTCFullYear());
oDate.setMonth(5);
writeDocument("月:"+oDate.getMonth());
oDate.setDate(1);
writeDocument("日:"+oDate.getDate());
oDate.setHours(16);
writeDocument("时:"+oDate.getHours());
oDate.setMinutes(58);
writeDocument("分:"+oDate.getMinutes());
oDate.setSeconds(59);
writeDocument("秒:"+oDate.getSeconds());
oDate.setMilliseconds(999);
writeDocument("毫秒:"+oDate.getMilliseconds());

var oPrintDate = new Date(2019, 5, 1, 15, 59, 59, 999); 
document.write(+oPrintDate.getFullYear()+'年'+(oPrintDate.getMonth()+1)+'月'
+oPrintDate.getDay()+'日'+weeks[oPrintDate.getDay()]+oPrintDate.getHours()+
':'+oPrintDate.getMinutes()+':'+oPrintDate.getSeconds()+':'+oPrintDate.getMilliseconds()+'<br>');