我在一家公司房地产代理公司工作，我正在创建一个供员工使用的内部页面，其中只包含一些小工具供他们使用。
我一直试图整理的一件事是租金计算器，给定租金和用户的租约到期日期，需要确定租约剩余的时间（从今天开始）然后告知该租约需要支付多少租金。
我已经让它工作了，大多数情况下，但你可以看到它相当长（我在某种程度上假设它必须）并且我觉得相当混乱：
//calculates the remaining rent left to pay for terminated leases
$("input[name='calcRent']").click(function() {
//gets rent and daily rent for later calculations
var rent = $("input[name='rentRent']").val();
var dailyRate = (rent * 12) / 365;
var leaseExpiry = $("input[name='leaseExpiry']").val();
var remRent = $("input[name='remRent']");
//breaks down lease expiry date and today's date into day, month, year parts
//so that units can be used in calculations
var ldd = leaseExpiry.substr(0,2);
ldd = parseInt(ldd, 10);
var lmm = leaseExpiry.substr(3,2);
lmm = parseInt(lmm, 10);
var lyyyy = leaseExpiry.substr(6,4);
lyyyy = parseInt(lyyyy, 10);
var date = new Date();
var tdd = date.getDate();
var tmm = date.getMonth()+1;
var tyyyy = date.getFullYear();
//if the expiry month is next year (or later) add 12 to expiry
//month value to make "lmm - tmm" calculation give positive value
if (lyyyy > tyyyy) {
lmm += (12 * (lyyyy - tyyyy));
}
//takes the current month from the expiry month to get the number of
//whole months left in the lease, then checks day values to see whether
//we have already passed the rent due date for this month (and so there's
//one less whole month left than we originally thought), taking 1 from
//wholeMths value if so
var wholeMths = lmm - tmm;
if (ldd == (tdd - 1)) {
wholeMths = wholeMths;
} else if (ldd < (tdd - 1)) {
wholeMths -= 1;
}
//works out if there are any days to be charged at daily rate (i.e. not
//part of a whole month). If today's date(tdd) == expiry date(ldd)+1 we have no
//leftover days (rental month runs like so: 12/04 - 11/05). If tdd > ldd+1
//(leftover days cross over a month end) we set checkMonth to true so the following
//if statement runs
var checkMonth = false;
var daysLeft = 0;
if (tdd == (ldd + 1)) {
daysLeft = 0;
} else if (tdd > ldd + 1) {
daysLeft = (31 - tdd) + ldd;
checkMonth = true;
} else {
daysLeft = ldd - tdd;
}
//as per the above line: "daysLeft = (31 - tdd) + ldd;" we assume months have 31 days
//as the majority do, this if checks whether the month end that we cross over with our
//leftover days actually has 30 days, if not we check whether it's February and whether
//it's a leap year so that we get the appropriate no. of days to charge for - if it meets
//any of these criteria the relevant no. of days are subtracted from daysLeft
if ((lmm == 05 || lmm == 07 || lmm == 10 || lmm == 12
|| lmm == 17 || lmm == 19 || lmm == 22 || lmm == 24) && checkMonth) {
daysLeft -= 1;
} else if ((lmm == 03 || lmm == 15) && checkMonth) {
if (lyyyy % 4 == 0) {
daysLeft -= 2;
} else {
daysLeft -= 3;
}
}
checkMonth = false;
var balance = (wholeMths * rent) + (daysLeft * dailyRate);
remRent.val(balance.toFixed(2));
});
其中一个特别困扰我的地方是租约到期后的一年。我没有理解如何整理当月的“价值”（正如你在决赛中看到的那样）。
对此提出的任何建议都会受到赞赏，因为评论的数量和数量似乎与实际代码有点不相称 - 但我认为它们目前是必要的，因为它不太清楚发生了什么。
谢谢，
答案 0 :(得分：1)
您已完成的工作做得很好，但您需要使用Date类在JavaScript中提供的内置日期计算。
具体来说，为了获得日期之间的天数，您可以使用以下逻辑：
var currentDate = new Date(); // This will get today's date
currentDate.setHours(0,0,0,0); // Remove time from consideration
// As recommended by @NickSlash
// The following get's the lease expiration date using the year,
// month and date that you have already extracted from the input
var leaseExpirationDate = new Date( lyyyy, lmm, ldd );
// The number of days remaining in the lease is simply the following:
var one_day = 1000*60*60*24;
var daysLeftInLease = (leaseExpirationDate - currentDate ) / one_day;
这种魔法的发生是因为Date类在内部将日期值保持为自1970年1月1日以来的毫秒数。因此，如果您减去两个Date个对象，则会获得它们之间的毫秒数。然后，您可以简单地将该值除以一天内的毫秒数，以获得日期之间的天数。