getTime() 返回从 1970 年 1 月 1 日至今的毫秒数，那么我用这个获取年为什么是+1900而不是+1970呢？var year=d.getYear()+1900;
date.getFullYear()请用 getFullYear()
getyear() 被废弃 参考：https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Global_Objects/Date/getYear
Return Value:
For years greater than or equal to 2000, the value returned by getYear is 100 or greater. For example, if the year is 2026, getYear returns 126.
For years between and including 1900 and 1999, the value returned by getYear is between 0 and 99. For example, if the year is 1976, getYear returns 76.
For years less than 1900, the value returned by getYear is less than 0. For example, if the year is 1800, getYear returns -100.