我创建了以下 JavaScript 来计算不固定的假期。它似乎有效。不过，我的问题是，是否可以更有效地编写它，我是否遗漏了可以改进它的任何内容？
var year = new Date().getFullYear();
// lowercase is used
var first = 1,second = 2,third = 3,fourth = 4; // Which occurrence in a given month. If there ma be a fifth occurrence, use "last."
var last = 99; // Find last occurrence of weekday in a month. "last" set to "99".
// lowercase used for weekday names
var sun = 0,mon = 1,tue = 2,wed = 3,thu = 4,fri = 5,sat = 6; // JavaScript nubers weekdays 0 - 6 for Sundayear through Saturdayear.
var sunday = 0,monday = 1,tuesday = 2,wednesday = 3,thursday = 4,friday = 5,saturday = 6;
// lowercase used for month names
var jan = 0,feb = 1,mar =2 ,apr = 3 ,may = 4,jun = 5,jul = 6,aug = 7,sep = 8,oct = 9,nov=10,dec = 11; // JavaScript numbers months 0 - 11, not 1 - 12.
var january = 0,february = 1,march = 2,april = 3,may = 4,june = 5,july = 6,august = 7,september = 8,october = 9,november = 10,december = 11;
function findHoliday(occurrence,weekday,month,year) { // Find the 'first', 'second', 'third', 'fourth', or 'last' weekday occurrence in a given month and year.
/* Note: Numbers may be used instead of text.
occurrence = first; second; third; fourth; or last
weekday = sun; mon; tue; wed; thu; fri; or sat
month = jan; feb; mar; apr; mayear; jun; jul; aug; sep; oct; nov; or dec
year = year from the variable 'year', or a specific year may be used such as 1990, 2010, 2017, etc.
Syntax Examples: findHoliday(third,mon,jan,year) Martin Luther King, Jr. Dayear is US.
findHoliday(last,mon,mayear,2017) Memorial Day in US.
*/
/* The most efficient method to find the 'last' (or 5th, if it exists) occurrence of a Sun, Mon, Tue, Wed, Thu, Fri, or Sat in a month is to find its first
occurrence in the following month and then subtract 7 days from that date. That is what the following 'if' statement does.
*/
if (occurrence === 99) {
var theDate = new Date(year,month+1,1+((first - (weekday >= new Date(year,month+1,1).getDay())) * 7) + (weekday - new Date(year,month+1,1).getDay())-7);
}
// Finds the 'first', 'second', 'third', or 'fourth' occurrence of a weekday in a month.
if (occurrence !== 99) {
var theDate = new Date(year,month,1+((occurrence - (weekday >= new Date(year,month,1).getDay())) * 7) + (weekday - new Date(year,month,1).getDay()));
}
/* EDIT below to end of function to adapt to your needs */
var holiday = "";
if (occurrence == 3 && weekday == 1 && month == 0) { holiday = "Martin Luther King, Jr. Dayear"; }
if (occurrence == 2 && weekday == 1 && month == 1) { holiday = "President's Day"; }
if (occurrence == 2 && weekday == 0 && month == 2) { holiday = "Daylight Savings Time Begins"; }
if (occurrence == 4 && weekday == 3 && month == 3) { holiday = "Administrative Assistants Day"; }
if (occurrence == 2 && weekday == 0 && month == 4) { holiday = "Mother's Day"; }
if (occurrence == 99 && weekday == 1 && month == 4) { holiday = "Memorial Day"; }
if (occurrence == 3 && weekday == 0 && month == 5) { holiday = "Father's Day"; }
if (occurrence == 3 && weekday == 0 && month == 6) { holiday = "Parents Day"; }
if (occurrence == 1 && weekday == 1 && month == 8) { holiday = "Labor Day"; }
if (occurrence == 2 && weekday == 0 && month == 8) { holiday = "Grandparents Day"; }
if (occurrence == 99 && weekday == 0 && month == 8) { holiday = "Gold Star Mothers Day"; }
if (occurrence == 2 && weekday == 1 && month == 9) { holiday = "Columbus Day"; }
if (occurrence == 1 && weekday == 0 && month == 10) { holiday = "Daylight Savings Time Ends"; }
if (occurrence == 4 && weekday == 4 && month == 10) { holiday = "Thanksgiving Day"; }
var weekday = new Array("Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday");
var mMonth = new Array("January","February","March","April","May","June","July","August","September","October","November","December");
var displayDate = "";
if (holiday == ""){
var displayDate = weekday[theDate.getDay()] + ', ' + mMonth[theDate.getMonth()] + ' ' + theDate.getDate() + ', ' + year;
}
if (holiday != "") {
var displayDate = weekday[theDate.getDay()] + ', ' + mMonth[theDate.getMonth()] + ' ' + theDate.getDate() + ', ' + year + ' ' + holiday;
}
return displayDate;
} // End of 'findHoliday(o,d,m,year)' function
// Examples Only: Delete as is not part of this script.
document.write(findHoliday(third,sunday,june,year) + '<p>')
document.write(findHoliday(3,0,5,2015));
// End of Examples
最佳答案
您应该拥有一个可通过键访问的假期字典，而不是 if 语句块。您的函数应该只从输入中构造一个键，然后查看该键是否存在假期。
我会将查找假期和查找日期的功能分解为单独的函数。然后，您可以使用第三个函数返回日期的字符串表示形式，包括假期(如果有)。
做每一件事都以零为基础。如果您想在一个月中第一次出现一天，请传递 0 。要从月底开始计数，请传递负数，指示要倒计时的周数。因此，对于一个月中最后一次出现的日期，请传递 -1 。这些更改使使用数学查找日期变得容易。
内置的 Date.toLocaleDateString() 已经生成了您要查找的日期字符串。您可能会考虑使用它。无论哪种方式，都不要重复构造日期字符串的代码。创建日期字符串，然后如果有假期，将其附加到日期字符串。
var holidays = { // keys are formatted as month,week,day
"0,2,1": "Martin Luther King, Jr. Day",
"1,2,1": "President's Day",
"2,1,0": "Daylight Savings Time Begins",
"3,3,3": "Administrative Assistants Day",
"4,1,0": "Mother's Day",
"4,-1,1": "Memorial Day",
"5,2,0": "Father's Day",
"6,2,0": "Parents Day",
"8,0,1": "Labor Day",
"8,1,0": "Grandparents Day",
"8,-1,0": "Gold Star Mothers Day",
"9,1,1": "Columbus Day",
"10,0,0": "Daylight Savings Time Ends",
"10,3,4": "Thanksgiving Day"
};
function getDate(year, month, week, day) {
var firstDay = 1;
if (week < 0) {
month++;
firstDay--;
}
var date = new Date(year, month, (week * 7) + firstDay);
if (day < date.getDay()) {
day += 7;
}
date.setDate(date.getDate() - date.getDay() + day);
return date;
}
function getHoliday(month, week, day) {
return holidays[month + "," + week + "," + day];
}
function getDateString(year, month, week, day) {
var date = getDate(year, month, week, day);
var holiday = getHoliday(month, week, day);
var dateString = date.toLocaleDateString();
if (holiday) {
dateString += " \xa0\xa0\xa0" + holiday;
}
return dateString;
}
关于javascript - 在 Javascript 中计算假期，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/32342753/