Javascr ipt的日期计算方法，包括两个日期之间相隔的天数，计算一个日期之前多少天，往后推算多少天得到的Date对象，方法可以直接调用，功能较全，即使不能直接调用，有一定基础的程序员也可以根据文档提供的方法自行进行改编-Javascr ipt date calculation methods, including two the number of days between dates, calculate how many days before a date, the projected number of days to get back the Date object, the method can directly call functions than the whole, if not called directly, there are certain basic The programmer also provides the method according to the document itself to adaptation