本文提供一段 JavaScript 代码，用于计算并格式化本周、本月、上月及本季度的开始与结束日期。代码包含日期格式化函数、月份天数判断逻辑，以及针对周、月、季度的具体日期计算算法，可直接复制使用。
JavaScript 获取指定时间段起止日期的实现代码
```javascript
```
代码如下：
/**
/**
* 获取本周、本季度、本月、上月的开始日期、结束日期
*/
*/
var now = new Date(); // 当前日期
var nowDayOfWeek = now.getDay(); // 今天本周的第几天
var nowDay = now.getDate(); // 当前日
var nowMonth = now.getMonth(); // 当前月
var nowYear = now.getYear(); // 当前年
nowYear += (nowYear < 2000) ? 1900 : 0; //
var lastMonthDate = new Date(); // 上月日期
lastMonthDate.setDate(1);
lastMonthDate.setMonth(lastMonthDate.getMonth() - 1);
var lastYear = lastMonthDate.getYear();
var lastMonth = lastMonthDate.getMonth();
// 格式化日期：yyyy-MM-dd
function formatDate(date) {
var myyear = date.getFullYear();
var mymonth = date.getMonth() + 1;
var myweekday = date.getDate();
if (mymonth < 10) {
mymonth = '0' + mymonth;
}
if (myweekday < 10) {
myweekday = '0' + myweekday;
}
return (myyear + '-' + mymonth + '-' + myweekday);
}
// 获得某月的天数
function getMonthDays(myMonth) {
var monthStartDate = new Date(nowYear, myMonth, 1);
var monthEndDate = new Date(nowYear, myMonth + 1, 1);
var days = (monthEndDate - monthStartDate) / (1000 * 60 * 60 * 24);
return days;
}
// 获得本季度的开始月份
function getQuarterStartMonth() {
var quarterStartMonth = 0;
if (nowMonth < 3) {
quarterStartMonth = 0;
}
if (2 < nowMonth && nowMonth < 6) {
quarterStartMonth = 3;
}
if (5 < nowMonth && nowMonth < 9) {
quarterStartMonth = 6;
}
if (nowMonth > 8) {
quarterStartMonth = 9;
}
return quarterStartMonth;
}
// 获得本周的开始日期
function getWeekStartDate() {
var weekStartDate = new Date(nowYear, nowMonth, nowDay - nowDayOfWeek);
return formatDate(weekStartDate);
}
// 获得本周的结束日期
function getWeekEndDate() {
var weekEndDate = new Date(nowYear, nowMonth, nowDay + (6 - nowDayOfWeek));
return formatDate(weekEndDate);
}
// 获得本月的开始日期
function getMonthStartDate() {
var monthStartDate = new Date(nowYear, nowMonth, 1);
return formatDate(monthStartDate);
}
// 获得本月的结束日期
function getMonthEndDate() {
var monthEndDate = new Date(nowYear, nowMonth, getMonthDays(nowMonth));
return formatDate(monthEndDate);
}
// 获得上月开始时候
function getLastMonthStartDate() {
var lastMonthStartDate = new Date(nowYear, lastMonth, 1);
return formatDate(lastMonthStartDate);
}
// 获得上月结束时候
function getLastMonthEndDate() {
var lastMonthEndDate = new Date(nowYear, lastMonth, getMonthDays(lastMonth));
return formatDate(lastMonthEndDate);
}
// 获得本季度的开始日期
function getQuarterStartDate() {
var quarterStartDate = new Date(nowYear, getQuarterStartMonth(), 1);
return formatDate(quarterStartDate);
}
// 或本季度的结束日期
function getQuarterEndDate() {
var quarterEndMonth = getQuarterStartMonth() + 2;
var quarterStartDate = new Date(nowYear, quarterEndMonth, getMonthDays(quarterEndMonth));
return formatDate(quarterStartDate);
}