var time=new Date(); time=time.setDate(time.getDate()+14);

这段代码的作用是创建一个Date对象并将其赋值给变量time，然后在time的基础上加上14天的毫秒数，最后将新的毫秒数赋回给time变量。实际上，这段代码有点问题，因为setDate()函数返回的是一个表示新日期的毫秒数，而不是一个Date对象。如果需要将时间增加14天，应该使用setUTCDate()函数而不是setDate()函数。以下是修改后的代码：

var time = new Date();
time.setUTCDate(time.getUTCDate() + 14);

这将在现有日期上增加14天，并将修改后的日期存储在time变量中。

相关问题

把它显示的日期改成 2023/05/23这样 // Get the current date var currentDate = new Date(); // Generate options for the date dropdown var selectDropdown = document.getElementById("date-dropdown"); for (var i = 0; i < 7; i++) { var option = document.createElement("option"); var date = new Date(currentDate); date.setDate(currentDate.getDate() + i); var dateString = date.toDateString(); option.text = dateString; option.value = dateString; selectDropdown.add(option);

可以这样修改代码，将日期格式改为 "YYYY/MM/DD" 的形式：

// Get the current date
var currentDate = new Date();

// Generate options for the date dropdown
var selectDropdown = document.getElementById("date-dropdown");
for (var i = 0; i < 7; i++) {
  var option = document.createElement("option");
  var date = new Date(currentDate);
  date.setDate(currentDate.getDate() + i);
  var year = date.getFullYear();
  var month = ("0" + (date.getMonth() + 1)).slice(-2);
  var day = ("0" + date.getDate()).slice(-2);
  var dateString = year + "/" + month + "/" + day;
  option.text = dateString;
  option.value = dateString;
  selectDropdown.add(option);
}

这样就可以将日期格式改为 "YYYY/MM/DD" 的形式了。

var today = new Date(); var currentQuarter = Math.floor((today.getMonth() + 1) / 3); var previousQuarter = currentQuarter - 1; var lastMonth = new Date(today.getFullYear(), today.getMonth(), today.getDate()); var yearQuarter = lastMonth.getFullYear(); if (previousQuarter < 1) { previousQuarter = 4; yearQuarter = yearQuarter - 1; } previousQuarter = previousQuarter.toString().padStart(2, '0'); var quer = yearQuarter + ' - ' + previousQuarter; var quarter = quer.slice(-1); var yearMonth = quer.substring(0, 4); let startMonth = (quarter - 1) * 3 + 1; let endMonth = startMonth + 2; let startDate = new Date(yearQuarter, startMonth - 1, 1); let endDate = new Date(yearQuarter, endMonth - 1, 1); endDate.setMonth(endDate.getMonth() + 1); endDate.setDate(endDate.getDate() - 1); startMonth = (startDate.getMonth() + 1).toString().padStart(2, '0'); endMonth = (endDate.getMonth() + 1).toString().padStart(2, '0'); document.getElementById('qt_1').value = startDate.getFullYear() + "-" + startMonth + "/" + endDate.getFullYear() + "-" + endMonth;这段代码导致我点开选择日历时日历的年显示的是1899，该怎么办

这段代码中涉及到了日期对象的操作，导致年份显示错误。在这里，endDate.setDate(endDate.getDate() - 1)这行代码是导致问题的原因。因为在设置endDate日期之后，又对它进行了修改，导致endDate的年份被修改为了默认值1899。

要解决这个问题，我们需要在endDate.setDate(endDate.getDate() - 1)之前获取endDate的年份，然后在修改之后将年份重新设置回去。

以下是修改后的代码：

var today = new Date();
var currentQuarter = Math.floor((today.getMonth() + 1) / 3);
var previousQuarter = currentQuarter - 1;
var lastMonth = new Date(today.getFullYear(), today.getMonth(), today.getDate());
var yearQuarter = lastMonth.getFullYear();

if (previousQuarter < 1) {
  previousQuarter = 4;
  yearQuarter = yearQuarter - 1;
}

previousQuarter = previousQuarter.toString().padStart(2, '0');
var quer = yearQuarter + ' - ' + previousQuarter;
var quarter = quer.slice(-1);
var yearMonth = quer.substring(0, 4);

let startMonth = (quarter - 1) * 3 + 1;
let endMonth = startMonth + 2;
let startDate = new Date(yearQuarter, startMonth - 1, 1);
let endDate = new Date(yearQuarter, endMonth - 1, 1);

// 获取endDate的年份
let endYear = endDate.getFullYear();

endDate.setDate(endDate.getDate() - 1);

// 将endDate的年份设置回去
endDate.setFullYear(endYear);

startMonth = (startDate.getMonth() + 1).toString().padStart(2, '0');
endMonth = (endDate.getMonth() + 1).toString().padStart(2, '0');
document.getElementById('qt_1').value = startDate.getFullYear() + "-" + startMonth + "/" + endDate.getFullYear() + "-" + endMonth;

这样修改后，应该就可以正确显示年份了。