js比较日期大小的函数（js计算两个日期相差天数）
前言
虽然现在处理日期方面已经有了很成熟的也很好用的库，例如（momentjs和date-fns），但是在实际开发中，我们有时候可能并不需要整个库。所以我就在下面整理了在前端开发时对日期时间的各种操作，也算是比较全的了。其中一部分来自自己，还有一部分来源于我们万能的网友~
获取当前时间戳
var timestamp = Date.parse(new Date()); //精确到秒var timestamp = (new Date()).valueOf(); //精确到毫秒var timestamp = new Date().getTime(); //精确到毫秒var timestamp = +new Date();var timestamp = Date.now();获取指定时间戳
var timestamp = (new Date(" 2019/10/24 08:00:00")).getTime();var timestamp = (new Date(" 2019-10-24 08:00:00")).getTime();获取当前时间的前一天/后一天的时间戳
var timestamp = +new Date() - 24*60*60*1000;var timestamp = +new Date() + 24*60*60*1000;今日零点时间戳
vartimestamp =newDate(newDate().toLocaleDateString()).getTime();今日最晚时间 23:59:59的时间戳
lettimestamp =newDate(newDate().toLocaleDateString()).getTime()+24*60*60*1000-1;获取当前时间的n天后的时间戳
/** * @param {number} n 天数 * @returns {Number} 返回值为时间毫秒值 */function toNextTimes(n){ let timestamp = +new Date() + n * 86400000; return timestamp;}本周第一天
/*** * @return {*} WeekFirstDay 返回本周第一天的时间 */function showWeekFirstDay(){ let Nowdate=new Date(); let WeekFirstDay=new Date(Nowdate-(Nowdate.getDay()-1)*86400000); return WeekFirstDay;}本周最后一天
/*** * @return {*} WeekLastDay 返回本周最后一天的时间 */function showWeekLastDay(){ let Nowdate=new Date(); let WeekFirstDay=new Date(Nowdate-(Nowdate.getDay()-1)*86400000); let WeekLastDay=new Date((WeekFirstDay/1000+6*86400)*1000); return WeekLastDay;}本月第一天
/*** * @return {*} MonthFirstDay 返回本月第一天的时间 */function showMonthFirstDay(){ let Nowdate=new Date(); let MonthFirstDay=new Date(Nowdate.getFullYear(),Nowdate.getMonth()); return MonthFirstDay;}本月最后一天
/*** * @return {*} MonthLastDay 返回本月最后一天的时间 */function showMonthLastDay(){ let Nowdate=new Date(); let MonthNextFirstDay=new Date(Nowdate.getFullYear(),Nowdate.getMonth()+1); let MonthLastDay=new Date(MonthNextFirstDay-86400000); return MonthLastDay;}日期转时间戳
/** * @param {String} time - 日期字符串，如'2018-8-8','2018,8,8','2018/8/8' * @returns {Number} 返回值为时间毫秒值 */function timeToTimestamp (time) { let date = new Date(time); let timestamp = date.getTime(); return timestamp;}格式化当前时间
/*** * @return {string} timeText 返回系统时间字符串 */function getdataTimeSec() { let time = new Date(); let weekDay; let year = time.getFullYear(); let month = time.getMonth() + 1; let day = time.getDate(); //获取时分秒 let h = time.getHours(); let m = time.getMinutes(); let s = time.getSeconds(); //检查是否小于10 h = check(h); m = check(m); s = check(s); let now_day = time.getDay(); switch (now_day) { case 0: { weekDay = "星期日" } break; case 1: { weekDay = "星期一" } break; case 2: { weekDay = "星期二" } break; case 3: { weekDay = "星期三" } break; case 4: { weekDay = "星期四" } break; case 5: { weekDay = "星期五" } break; case 6: { weekDay = "星期六" } break; case 7: { weekDay = "星期日" } break; } let timeText = year + "年" + month + "月" + day + "日 " + " " + weekDay + " " + h + ":" + m +":" + s; return timeText}返回指定时间戳之间的时间间隔
/** * @param {*} startTime 开始时间的时间戳 * @param {*} endTime 结束时间的时间戳 * @return {string} str 返回时间字符串 */function getTimeInterval(startTime, endTime) { let runTime = parseInt((endTime - startTime) / 1000); let year = Math.floor(runTime / 86400 / 365); runTime = runTime % (86400 * 365); let month = Math.floor(runTime / 86400 / 30); runTime = runTime % (86400 * 30); let day = Math.floor(runTime / 86400); runTime = runTime % 86400; let hour = Math.floor(runTime / 3600); runTime = runTime % 3600; let minute = Math.floor(runTime / 60); runTime = runTime % 60; let second = runTime; let str = ''; if (year &> 0) { str = year + '年'; } if (year &<= 0 &&&& month &> 0) { str = month + '月'; } if (year &<= 0 &&&& month &<= 0 &&&& day &> 0) { str = day + '天'; } if (year &<= 0 &&&& month &<= 0 &&&& day &<= 0 &&&& hour &> 0) { str = hour + '小时'; } if (year &<= 0 &&&& month &<= 0 &&&& day &<= 0 &&&& hour &<= 0 &&&& minute &> 0) { str = minute + '分钟'; } if (year &<= 0 &&&& month &<= 0 &&&& day &<= 0 &&&& hour &<= 0 &&&& minute &<= 0 &&&& second &> 0) { str += second + '秒'; } str += '前'; return str;}按类型格式化日期
/** * @param {*} date 具体日期变量 * @param {string} dateType 需要返回类型 * @return {string} dateText 返回为指定格式的日期字符串 */function getFormatDate(date, dateType) { let dateObj = new Date(date); let month = dateObj.getMonth() + 1; let strDate = dateObj.getDate(); let hours = dateObj.getHours(); let minutes = dateObj.getMinutes(); let seconds = dateObj.getSeconds(); if (month &>= 1 &&&& month &<= 9) { month = "0" + month; } if (strDate &>= 0 &&&& strDate &<= 9) { strDate = "0" + strDate; } if (hours &>= 0 &&&& hours &<= 9) { hours = "0" + hours } if (minutes &>= 0 &&&& minutes &<= 9) { minutes = "0" + minutes } if (seconds &>= 0 &&&& seconds &<= 9) { seconds = "0" + seconds } let dateText = dateObj.getFullYear() + '年' + (dateObj.getMonth() + 1) + '月' + dateObj.getDate() + '日'; if (dateType == "yyyy-mm-dd") { dateText = dateObj.getFullYear() + '-' + (dateObj.getMonth() + 1) + '-' + dateObj.getDate(); } if (dateType == "yyyy.mm.dd") { dateText = dateObj.getFullYear() + '.' + (dateObj.getMonth() + 1) + '.' + dateObj.getDate(); } if (dateType == "yyyy-mm-dd MM:mm:ss") { dateText = dateObj.getFullYear() + '-' + month + '-' + strDate + ' ' + hours + ":" + minutes + ":" + seconds; } if (dateType == "mm-dd MM:mm:ss") { dateText = month + '-' + strDate + ' ' + hours + ":" + minutes + ":" + seconds; } if (dateType == "yyyy年mm月dd日 MM:mm:ss") { dateText = dateObj.getFullYear() + '年' + month + '月' + strDate + '日' + ' ' + hours + ":" + minutes + ":" + seconds; } return dateText; }判断是否为闰年
/*** @param {number} year 要判断的年份* @return {boolean} 返回布尔值*/function leapYear(year) { return !(year % (year % 100 ? 4 : 400));}返回两个年份之间的闰年
/*** @param {number} start 开始年份* @param {number} end 结束年份* @return {array} arr 返回符合闰年的数组*/function leapYears(start, end) { let arr = &[]; for (var i=start; i&<end; i++) { if ( leapYear(i) ) { arr.push(i) } } return arr}判断时间格式是否有效
/*** 短时间，如 (10:24:06)* @param {string} str 需要验证的短时间* @return {boolean} 返回布尔值*/function isTime(str) { var a = str.match(/^(\d{1,2})(:)?(\d{1,2})\2(\d{1,2})$/); if (a == null) { return false; } if (a&[1] &>= 24 || a&[3] &>= 60 || a&[4] &>= 60) { return false } return true;}/*** 短日期，形如 (2019-10-24)* @param {string} str 需要验证的短时间* @return {boolean} 返回布尔值*/function strDateTime(str){ var result = str.match(/^(\d{1,4})(-|\/)(\d{1,2})\2(\d{1,2})$/); if (result == null) return false; var d = new Date(result&[1], result&[3] - 1, result&[4]); return (d.getFullYear() == result&[1] &&&& d.getMonth() + 1 == result&[3] &&&& d.getDate() == result&[4]);}/*** 长日期时间，形如 (2019-10-24 10:24:06)* @param {string} str 需要验证的短时间* @return {boolean} 返回布尔值*/function strDateTime(str){ var result = str.match(/^(\d{4})(-|\/)(\d{1,2})\2(\d{1,2}) (\d{1,2}):(\d{1,2}):(\d{1,2})$/); if (result == null) return false; var d = new Date(result&[1], result&[3] - 1, result&[4], result&[5], result&[6], result&[7]); return (d.getFullYear() == result&[1] &&&& (d.getMonth() + 1) == result&[3] &&&& d.getDate() == result&[4] &&&& d.getHours() == result&[5] &&&& d.getMinutes() == result&[6] &&&& d.getSeconds() == result&[7]);}验证日期大小
/*** 例："2019-10-24" 和 "2019-10-25"* @param {string} d1需要验证的日期1* @param {string} d2需要验证的日期2* @return {boolean} 返回布尔值*/function compareDate(d1, d2) { return ((new Date(d1.replace(/-/g, "\/"))) &< (new Date(d2.replace(/-/g, "\/"))));}验证一个日期是不是今天
/*** @param {string} val 需要验证的日期* @return {boolean} 返回布尔值*/function isToday(val){ return new Date().toLocaleDateString() == new Date(val).toLocaleDateString();}验证传入的日期是否是昨天
/*** @param {string} val 需要验证的日期* @return {boolean} 返回布尔值*/function isYesterday(val) { var today = new Date(); var yesterday = new Date(now - 1000 * 60 * 60 * 24); var test = new Date(val); if (yesterday.getYear() === test.getYear() &&&& yesterday.getMonth() === test.getMonth() &&&& yesterday.getDate() === test.getDate()) { return true; } else { return false; }}设置几天后的日期
/*** @param {string} date 起始日期* @param {number} day 向后的天数* @return {string} 返回想要得到的日期*/function convertDate (date, day) { let tempDate = new Date(date); tempDate.setDate(tempDate.getDate()+day); let Y = tempDate.getFullYear(); let M = tempDate.getMonth()+1 &< 10 ? '0'+(tempDate.getMonth()+1) : tempDate.getMonth()+1; let D = tempDate.getDate() &< 10 ? '0'+(tempDate.getDate()) : tempDate.getDate(); let result = Y + "-" + M + "-" + D return result;}写在最后
若上面函数有错误，或者还有工作中遇到，但是上面没有写到的，欢迎指出来~