如何将字符串转换为JavaScript日期对象?

var st = "date in some format"
var dt = new Date();

var dt_st = // st in Date format, same as dt.

当前回答

还有一种方法是在格式字符串上构建一个带有命名捕获组的正则表达式,然后使用该正则表达式从日期字符串中提取日、月和年:

function parseDate(dateStr, format) { const regex = format.toLocaleLowerCase() .replace(/\bd+\b/, '(?<day>\\d+)') .replace(/\bm+\b/, '(?<month>\\d+)') .replace(/\by+\b/, '(?<year>\\d+)') const parts = new RegExp(regex).exec(dateStr) || {}; const { year, month, day } = parts.groups || {}; return parts.length === 4 ? new Date(year, month-1, day) : undefined; } const printDate = x => console.log(x ? x.toLocaleDateString() : x); printDate(parseDate('05/11/1896', 'dd/mm/YYYY')); printDate(parseDate('07-12-2000', 'dd-mm-yy')); printDate(parseDate('07:12:2000', 'dd:mm:yy')); printDate(parseDate('2017/6/3', 'yy/MM/dd')); printDate(parseDate('2017-6-15', 'y-m-d')); printDate(parseDate('2015 6 25', 'y m d')); printDate(parseDate('2015625', 'y m d')); // bad format

其他回答

我已经创建了parseDateTime函数将字符串转换为日期对象,它在所有浏览器(包括IE浏览器)中工作,检查是否有人需要,引用 https://github.com/Umesh-Markande/Parse-String-to-Date-in-all-browser

    function parseDateTime(datetime) {
            var monthNames = [
                "January", "February", "March",
                "April", "May", "June", "July",
                "August", "September", "October",
                "November", "December"
              ];
            if(datetime.split(' ').length == 3){
                var date = datetime.split(' ')[0];
                var time = datetime.split(' ')[1].replace('.00','');
                var timearray = time.split(':');
                var hours = parseInt(time.split(':')[0]);
                var format = datetime.split(' ')[2];
                var bits = date.split(/\D/);
                date = new Date(bits[0], --bits[1], bits[2]); /* if you change format of datetime which is passed to this function, you need to change bits e.x ( bits[0], bits[1], bits[2 ]) position as per date, months and year it represent bits array.*/
                var day = date.getDate();
                var monthIndex = date.getMonth();
                var year = date.getFullYear();
                if ((format === 'PM' || format === 'pm') && hours !== 12) {
                    hours += 12;
                    try{  time = hours+':'+timearray[1]+':'+timearray[2] }catch(e){ time = hours+':'+timearray[1] }
                } 
                var formateddatetime = new Date(monthNames[monthIndex] + ' ' + day + '  ' + year + ' ' + time);
                return formateddatetime;
            }else if(datetime.split(' ').length == 2){
                var date = datetime.split(' ')[0];
                var time = datetime.split(' ')[1];
                var bits = date.split(/\D/);
                var datetimevalue = new Date(bits[0], --bits[1], bits[2]); /* if you change format of datetime which is passed to this function, you need to change bits e.x ( bits[0], bits[1], bits[2 ]) position as per date, months and year it represent bits array.*/
                var day = datetimevalue.getDate();
                var monthIndex = datetimevalue.getMonth();
                var year = datetimevalue.getFullYear();
                var formateddatetime = new Date(monthNames[monthIndex] + ' ' + day + '  ' + year + ' ' + time);
                return formateddatetime;
            }else if(datetime != ''){
                var bits = datetime.split(/\D/);
                var date = new Date(bits[0], --bits[1], bits[2]); /* if you change format of datetime which is passed to this function, you need to change bits e.x ( bits[0], bits[1], bits[2 ]) position as per date, months and year it represent bits array.*/
                return date;
            }
            return datetime;
        }

    var date1 = '2018-05-14 05:04:22 AM';   // yyyy-mm-dd hh:mm:ss A
    var date2 = '2018/05/14 05:04:22 AM';   // yyyy/mm/dd hh:mm:ss A
    var date3 = '2018/05/04';   // yyyy/mm/dd
    var date4 = '2018-05-04';   // yyyy-mm-dd
    var date5 = '2018-05-14 15:04:22';   // yyyy-mm-dd HH:mm:ss
    var date6 = '2018/05/14 14:04:22';   // yyyy/mm/dd HH:mm:ss

    console.log(parseDateTime(date1))
    console.log(parseDateTime(date2))
    console.log(parseDateTime(date3))
    console.log(parseDateTime(date4))
    console.log(parseDateTime(date5))
    console.log(parseDateTime(date6))

**Output---**
Mon May 14 2018 05:04:22 GMT+0530 (India Standard Time)
Mon May 14 2018 05:04:22 GMT+0530 (India Standard Time)
Fri May 04 2018 00:00:00 GMT+0530 (India Standard Time)
Fri May 04 2018 00:00:00 GMT+0530 (India Standard Time)
Mon May 14 2018 15:04:22 GMT+0530 (India Standard Time)
Mon May 14 2018 14:04:22 GMT+0530 (India Standard Time)

你可以使用regex解析字符串以详细的时间,然后创建日期或任何返回格式,如:

//example : let dateString = "2018-08-17 01:02:03.4"

function strToDate(dateString){
    let reggie = /(\d{4})-(\d{2})-(\d{2}) (\d{2}):(\d{2}):(\d{2}).(\d{1})/
  , [,year, month, day, hours, minutes, seconds, miliseconds] = reggie.exec(dateString)
  , dateObject = new Date(year, month-1, day, hours, minutes, seconds, miliseconds);
  return dateObject;
}
alert(strToDate(dateString));

如果要从“dd/MM/yyyy”格式转换。这里有一个例子:

var pattern = /^(\d{1,2})\/(\d{1,2})\/(\d{4})$/;
var arrayDate = stringDate.match(pattern);
var dt = new Date(arrayDate[3], arrayDate[2] - 1, arrayDate[1]);

此解决方案适用于IE 9以下版本。

var st = "26.04.2013";
var pattern = /(\d{2})\.(\d{2})\.(\d{4})/;
var dt = new Date(st.replace(pattern,'$3-$2-$1'));

输出将是:

dt => Date {Fri Apr 26 2013}

作为这里所解释的内容的一个插件,您可以使用new Date()创建日期,并使用非常有用的toLocaleDateString()函数对其进行格式化

一个例子:

console.log(new Date('1970-01-01').toLocaleDateString('es-ES')) //——>输出'1/1/1970'