周数(Week Number, WeekNum)计算

jQuery UI v1.8rc 版的日历控件已经非常完善，比之 v1.7.1 已经支持显示周数(WeekNum)，而且计算 WeekNum 的算法可以自定义；而 My97DatePicker 的算法又有Bug。对于两年交接的周，有两种常见的算法：

每年 1月 1日所在的周均为该年的第 1周（如MS Excel的WeekNum()函数和 jQuery 实现）；

1/* Set as calculateWeek to determine the week of the year based on the ISO 8601 definition.
2   @param  date  Date - the date to get the week for
3   @return  number - the number of the week within the year that contains this date */
4iso8601Week: function(date) {
5    var checkDate = new Date(date.getTime());
6    // Find Thursday of this week starting on Monday
7    checkDate.setDate(checkDate.getDate() + 4 - (checkDate.getDay() || 7));
8    var time = checkDate.getTime();
9    checkDate.setMonth(0); // Compare with Jan 1
10    checkDate.setDate(1);
11    return Math.floor(Math.round((time - checkDate) / 86400000) / 7) + 1;
12},

每年最后 1天所在的周

1/**
2 * @param date {Date} 每周第 1天。
3 * @return {Number}
4 */
5calculateWeek:function(date){
6    var d = new Date(date.getTime()+(6*86400000)), t=d.getTime();
7    var start = new Date(d.getTime()); start.setMonth(0); start.setDate(1);
8    return Math.floor((t - start.getTime())/86400000/7)+1;
9}

而从自然语言中来说，这交接的一周即可以是头一年的最后一周，也可以是后一年的第 1周。

Tags: JavaScript, 算法

Published on 2010-03-16

周数(Week Number, WeekNum)计算#

周数(Week Number, WeekNum)计算