???????????
???????????????????new Date()?????????Date????
????new Date();//Date {Mon Jun 15 2015 15:53:16 GMT+0800}
???????????new Date(????)??????????????????????Date????
????new Date(1330334847297);//Date {Mon Feb 27 2012 17:27:27 GMT+0800}
????BUG????
?????????????????????е?Date????????Date?????????????????????????????????????
????var a=new Date();
????a.getTime();//1434355104731
????var b=new Date(a);
????b.getTime();//1434355104000????????????????????
??????bug??????????IE??????????FireFox?????????У?Chrome????????

???????????
???????嵼?μ??????????δ????????????????????У?
???????????????ECMA?й漲???????????????κη?漲????÷???????????????