Parsing a string to a date in JavaScript

The best string format for string parsing is the date ISO format together with the JavaScript Date object constructor.

Examples of ISO format: YYYY-MM-DD or YYYY-MM-DDTHH:MM:SS.

But wait! Just using the "ISO format" doesn't work reliably by itself. String are sometimes parsed as UTC and sometimes as localtime (based on browser vendor and version). The best practice should always be to store dates as UTC and make computations as UTC.

To parse a date as UTC, append a Z - e.g.: new Date('2011-04-11T10:20:30Z').

To display a date in UTC, use .toUTCString(),
to display a date in user's local time, use .toString().

More info on MDN | Date and this answer.

For old Internet Explorer compatibility (IE versions less than 9 do not support ISO format in Date constructor), you should split datetime string representation to it's parts and then you can use constructor using datetime parts, e.g.: new Date('2011', '04' - 1, '11', '11', '51', '00'). Note that the number of the month must be 1 less.

Alternate method - use an appropriate library:

You can also take advantage of the library Moment.js that allows parsing date with the specified time zone.

---

Unfortunately I found out that

var mydate = new Date('2014-04-03'); console.log(mydate.toDateString());

returns "Wed Apr 02 2014". I know it sounds crazy, but it happens for some users.

The bulletproof solution is the following:

var parts ='2014-04-03'.split('-'); // Please pay attention to the month (parts[1]); JavaScript counts months from 0: // January - 0, February - 1, etc. var mydate = new Date(parts[0], parts[1] - 1, parts[2]); console.log(mydate.toDateString());

---

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

And the output will be:

dt => Date {Fri Apr 26 2013}

---

function stringToDate(_date,_format,_delimiter)
{
            var formatLowerCase=_format.toLowerCase();
            var formatItems=formatLowerCase.split(_delimiter);
            var dateItems=_date.split(_delimiter);
            var monthIndex=formatItems.indexOf("mm");
            var dayIndex=formatItems.indexOf("dd");
            var yearIndex=formatItems.indexOf("yyyy");
            var month=parseInt(dateItems[monthIndex]);
            month-=1;
            var formatedDate = new Date(dateItems[yearIndex],month,dateItems[dayIndex]);
            return formatedDate;
}

stringToDate("17/9/2014","dd/MM/yyyy","/");
stringToDate("9/17/2014","mm/dd/yyyy","/")
stringToDate("9-17-2014","mm-dd-yyyy","-")

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Recommendation: I recommend to use a package for dates that contains a lot of formats because the timezone and format time management is really a big problem, moment js solve a lot of formats. You could parse easily date from a simple string to date but I think that is a hard work to support all formats and variations of dates.

Update: Moment is now deprecated, A good alternative for moment is datefns https://date-fns.org/

moment.js (http://momentjs.com/) is a complete and good package for use dates and supports ISO 8601 strings.

You could add a string date and format.

moment("12-25-1995", "MM-DD-YYYY");

And you could check if a date is valid.

moment("not a real date").isValid(); //Returns false

Some display examples

let dt = moment("02-01-2019", "MM-DD-YYYY");
console.log(dt.fromNow()+' |'+dt.format('LL')) 
// output: "3 months ago | February 1, 2019"

See documentation http://momentjs.com/docs/#/parsing/string-format/

---

Pass it as an argument to Date():

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

You can access the date, month, year using, for example: dt.getMonth().

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If you can use the terrific luxon library you can easily parse your date using e.g.

var luxonDate = DateTime.fromISO("2014-09-15T09:00:00");

and can access the JS date object via

luxonDate().toJSDate();

The old answer used MomentJS

var momentDate = moment("2014-09-15 09:00:00");
momentDate ().toDate();

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For those who are looking for a tiny and smart solution:

String.prototype.toDate = function(format)
{
  var normalized      = this.replace(/[^a-zA-Z0-9]/g, '-');
  var normalizedFormat= format.toLowerCase().replace(/[^a-zA-Z0-9]/g, '-');
  var formatItems     = normalizedFormat.split('-');
  var dateItems       = normalized.split('-');

  var monthIndex  = formatItems.indexOf("mm");
  var dayIndex    = formatItems.indexOf("dd");
  var yearIndex   = formatItems.indexOf("yyyy");
  var hourIndex     = formatItems.indexOf("hh");
  var minutesIndex  = formatItems.indexOf("ii");
  var secondsIndex  = formatItems.indexOf("ss");

  var today = new Date();

  var year  = yearIndex>-1  ? dateItems[yearIndex]    : today.getFullYear();
  var month = monthIndex>-1 ? dateItems[monthIndex]-1 : today.getMonth()-1;
  var day   = dayIndex>-1   ? dateItems[dayIndex]     : today.getDate();

  var hour    = hourIndex>-1      ? dateItems[hourIndex]    : today.getHours();
  var minute  = minutesIndex>-1   ? dateItems[minutesIndex] : today.getMinutes();
  var second  = secondsIndex>-1   ? dateItems[secondsIndex] : today.getSeconds();

  return new Date(year,month,day,hour,minute,second);
};

Example:

"22/03/2016 14:03:01".toDate("dd/mm/yyyy hh:ii:ss");
"2016-03-29 18:30:00".toDate("yyyy-mm-dd hh:ii:ss");

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Just new Date(st);

Assuming that it's the proper format.

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new Date(2000, 10, 1) will give you "Wed Nov 01 2000 00:00:00 GMT+0100 (CET)"

See that 0 for month gives you January

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If you want to convert from the format "dd/MM/yyyy". Here is an example:

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]);

This solution works in IE versions less than 9.

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Timestamps should be casted to a Number

var ts = '1471793029764';
ts = Number(ts); // cast it to a Number
var date = new Date(ts); // works

var invalidDate = new Date('1471793029764'); // does not work. Invalid Date

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Date.parse almost gets you what you want. It chokes on the am/pm part, but with some hacking you can get it to work:

var str = 'Sun Apr 25, 2010 3:30pm',
    timestamp;

timestamp = Date.parse(str.replace(/[ap]m$/i, ''));

if(str.match(/pm$/i) >= 0) {
    timestamp += 12 * 60 * 60 * 1000;
}

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Performance

Today (2020.05.08) I perform tests for chosen solutions - for two cases: input date is ISO8601 string (Ad,Bd,Cd,Dd,Ed) and input date is timestamp (At, Ct, Dt). Solutions Bd,Cd,Ct not return js Date object as results, but I add them because they can be useful but I not compare them with valid solutions. This results can be useful for massive date parsing.

Conclusions

Solution new Date (Ad) is 50-100x faster than moment.js (Dd) for all browsers for ISO date and timestamp

Solution new Date (Ad) is ~10x faster than parseDate (Ed)

Solution Date.parse(Bd) is fastest if wee need to get timestamp from ISO date on all browsers

https://i.stack.imgur.com/YjDwQ.png

Details

I perform test on MacOs High Sierra 10.13.6 on Chrome 81.0, Safari 13.1, Firefox 75.0. Solution parseDate (Ed) use new Date(0) and manually set UTC date components.

let ds = '2020-05-14T00:00Z'; // Valid ISO8601 UTC date let ts = +'1589328000000'; // timestamp let Ad = new Date(ds); let Bd = Date.parse(ds); let Cd = moment(ds); let Dd = moment(ds).toDate(); let Ed = parseDate(ds); let At = new Date(ts); let Ct = moment(ts); let Dt = moment(ts).toDate(); log = (n,d) => console.log(`${n}: ${+d} ${d}`); console.log('from date string:', ds) log('Ad', Ad); log('Bd', Bd); log('Cd', Cd); log('Dd', Dd); log('Ed', Ed); console.log('from timestamp:', ts) log('At', At); log('Ct', Ct); log('Dt', Dt); function parseDate(dateStr) { let [year,month,day] = dateStr.split(' ')[0].split('-'); let d=new Date(0); d.setUTCFullYear(year); d.setUTCMonth(month-1); d.setUTCDate(day) return d; } This snippet only presents used soultions

Results for chrome

https://i.stack.imgur.com/MzeOY.png

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Convert to format pt-BR:

    var dateString = "13/10/2014";
    var dataSplit = dateString.split('/');
    var dateConverted;

    if (dataSplit[2].split(" ").length > 1) {

        var hora = dataSplit[2].split(" ")[1].split(':');
        dataSplit[2] = dataSplit[2].split(" ")[0];
        dateConverted = new Date(dataSplit[2], dataSplit[1]-1, dataSplit[0], hora[0], hora[1]);

    } else {
        dateConverted = new Date(dataSplit[2], dataSplit[1] - 1, dataSplit[0]);
    }

I hope help somebody!!!

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That's the best and simpler solution in my view:

Just concatenate your date string (using ISO format) with "T00:00:00" in the end and use the JavaScript Date() constructor, like the example below.

const dateString = '2014-04-03'
var mydate = new Date(dateString + "T00:00:00");
console.log(mydate.toDateString());

And just a few details about the solution above (but optional reading):

In ISO format, if you provide time and Z is not present in the end of string, the date will be local time zone instead of UTC time zone. That means, when setting a date in this way, without specifying the time zone, JavaScript will use the local browser's time zone. And when getting a date, without specifying the time zone as well, the result is also converted to the browser's time zone. And, by default, almost every date method in JavaScript (except one) gives you a date/time in local time zone as well (you only get UTC if you specify UTC). So, using in local/browser time zone you probably won't get unwanted results because difference between your local/browse time zone and the UTC time zone, which is one of the main complaints with date string conversion. But if you will use this solution, understand your context and be aware of what you are doing. And also be careful that omitting T or Z in a date-time string can give different results in different browsers.

Important to note that the example above will give you exactly the same return to this example below, that is the second most voted answer in this question:

var parts ='2014-04-03'.split('-');
// Please pay attention to the month (parts[1]); JavaScript counts months from 0:
// January - 0, February - 1, etc.
var mydate = new Date(parts[0], parts[1] - 1, parts[2]); 
console.log(mydate.toDateString());

The main difference is that the first example provided here is simpler and even more error proof than the second one (at least in my view, as explained below).

Because if you call the JavaScript Date() constructor date with just one date-string argument in ISO format (first example), it doesn't accept values above its logical limit (so, if you give 13 as month or 32 as day, you get Invalid Date).

But when you use the same constructor with multiple date-arguments (second example), parameters above it logical limit will be adjusted to the adjacent value and you won't get Invalid Date Error (so, if you give 13 as month, it will adjust to 1, instead of give you an Invalid Date).

Or an alternative (and third) solution would be mix both, use the first example just to validate the date-string and if it is valid use the second example (so you avoid possible browsers inconsistences of the first example and at the same time avoid the permission of parameters above it logical limit of the second example).

Like so (accepting partial dates as well):

function covertStringToDate(dateString) {
    //dateString should be in ISO format: "yyyy-mm-dd", "yyyy-mm" or "yyyy"
    if(new Date(dateString).toString() === "Invalid Date") {
        return false
    } else {
        const onlyNumbers = dateString.replace(/\D/g, ""); 
        const year = onlyNumbers.slice(0,4) 
        const month = onlyNumbers.slice(4,6)
        const day = onlyNumbers.slice(6,8)
        if(!month){
            return(new Date(year))
        } else if (!day) {
            return(new Date(year, month - 1))
        } else {
            return(new Date(year, month - 1, day))
        }        
    }
}

And a fourth alternative (and last suggestion) would be to use an appropriate third library (like moment or date-fns)

References:

https://www.w3schools.com/js/js_date_formats.asp

https://css-tricks.com/everything-you-need-to-know-about-date-in-javascript/

https://developer.mozilla.org/pt-BR/docs/Web/JavaScript/Reference/Global_Objects/Date#parameters

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I have created a fiddle for this, you can use toDate() function on any date string and provide the date format. This will return you a Date object. https://jsfiddle.net/Sushil231088/q56yd0rp/

"17/9/2014".toDate("dd/MM/yyyy", "/")

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For сonverting string to date in js i use http://momentjs.com/

moment().format('MMMM Do YYYY, h:mm:ss a'); // August 16th 2015, 4:17:24 pm
moment().format('dddd');                    // Sunday
moment().format("MMM Do YY");               // Aug 16th 15
moment().format('YYYY [escaped] YYYY');     // 2015 escaped 2015
moment("20111031", "YYYYMMDD").fromNow(); // 4 years ago
moment("20120620", "YYYYMMDD").fromNow(); // 3 years ago
moment().startOf('day').fromNow();        // 16 hours ago
moment().endOf('day').fromNow();          // in 8 hours

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I made this function to convert any Date object to a UTC Date object.

function dateToUTC(date) {
    return new Date(date.getUTCFullYear(), date.getUTCMonth(), date.getUTCDate(), date.getUTCHours(), date.getUTCMinutes(), date.getUTCSeconds());
}


dateToUTC(new Date());

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You Can try this:

function formatDate(userDOB) { const dob = new Date(userDOB); const monthNames = [ 'January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December' ]; const day = dob.getDate(); const monthIndex = dob.getMonth(); const year = dob.getFullYear(); // return day + ' ' + monthNames[monthIndex] + ' ' + year; return `${day} ${monthNames[monthIndex]} ${year}`; } console.log(formatDate('1982-08-10'));

---

This answer is based on Kassem's answer but it also handles two-digit years. I submitted an edit to Kassem's answer, but in case it wasn't approved, I'm also submitting this as a separate answer.

function stringToDate(_date,_format,_delimiter) {
        var formatLowerCase=_format.toLowerCase();
        var formatItems=formatLowerCase.split(_delimiter);
        var dateItems=_date.split(_delimiter);
        var monthIndex=formatItems.indexOf("mm");
        var dayIndex=formatItems.indexOf("dd");
        var yearIndex=formatItems.indexOf("yyyy");
        var year = parseInt(dateItems[yearIndex]); 
        // adjust for 2 digit year
        if (year < 100) { year += 2000; }
        var month=parseInt(dateItems[monthIndex]);
        month-=1;
        var formatedDate = new Date(year,month,dateItems[dayIndex]);
        return formatedDate;
}

stringToDate("17/9/14","dd/MM/yyyy","/");
stringToDate("17/9/2014","dd/MM/yyyy","/");
stringToDate("9/17/2014","mm/dd/yyyy","/")
stringToDate("9-17-2014","mm-dd-yyyy","-")

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Yet another way to do it:

String.prototype.toDate = function(format) {
    format = format || "dmy";
    var separator = this.match(/[^0-9]/)[0];
    var components = this.split(separator);
    var day, month, year;
    for (var key in format) {
        var fmt_value = format[key];
        var value = components[key];
        switch (fmt_value) {
            case "d":
                day = parseInt(value);
                break;
            case "m":
                month = parseInt(value)-1;
                break;
            case "y":
                year = parseInt(value);
        }
    }
    return new Date(year, month, day);
};
a = "3/2/2017";
console.log(a.toDate("dmy"));
// Date 2017-02-03T00:00:00.000Z

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var date = new Date(year, month, day);

or

var date = new Date('01/01/1970');

date string in format '01-01-1970' will not work in FireFox, So better use "/" instead of "-" in date format string.

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If you need to check the contents of the string before converting to Date format:

// Convert 'M/D/YY' to Date()
mdyToDate = function(mdy) {
  var d = mdy.split(/[\/\-\.]/, 3);

  if (d.length != 3) return null;

  // Check if date is valid
  var mon = parseInt(d[0]), 
      day = parseInt(d[1]),
      year= parseInt(d[2]);
  if (d[2].length == 2) year += 2000;
  if (day <= 31 && mon <= 12 && year >= 2015)
    return new Date(year, mon - 1, day);

  return null; 
}

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I have created parseDateTime function to convert the string to date object and it is working in all browser (including IE browser), check if anyone required, reference 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)

---

You can using regex to parse string to detail time then create date or any return format like :

//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));

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ISO 8601-esque datestrings, as excellent as the standard is, are still not widely supported.

This is a great resource to figure out which datestring format you should use:

http://dygraphs.com/date-formats.html

Yes, that means that your datestring could be as simple as as opposed to

"2014/10/13 23:57:52" instead of "2014-10-13 23:57:52"

---

                //little bit of code for Converting dates 

                var dat1 = document.getElementById('inputDate').value;
                var date1 = new Date(dat1)//converts string to date object
                alert(date1);
                var dat2 = document.getElementById('inputFinishDate').value;
                var date2 = new Date(dat2)
                alert(date2);

---

use this code : (my problem was solved with this code)

function dateDiff(date1, date2){
var diff = {}                           // Initialisation du retour
var tmp = date2 - date1;

tmp = Math.floor(tmp/1000);             // Nombre de secondes entre les 2 dates
diff.sec = tmp % 60;                    // Extraction du nombre de secondes

tmp = Math.floor((tmp-diff.sec)/60);    // Nombre de minutes (partie entière)
diff.min = tmp % 60;                    // Extraction du nombre de minutes

tmp = Math.floor((tmp-diff.min)/60);    // Nombre d'heures (entières)
diff.hour = tmp % 24;                   // Extraction du nombre d'heures

tmp = Math.floor((tmp-diff.hour)/24);   // Nombre de jours restants
diff.day = tmp;

return diff;

}

---

I wrote a reusable function that i use when i get date strings from the server.
you can pass your desired delimiter( / - etc..) that separates the day month and year in order to use the split() method.
you can see & test it on this working example.

<!DOCTYPE html>
<html>
  <head>
    <style>
    </style>
  </head>
  <body>
    <div>
      <span>day:
      </span> 
      <span id='day'>
      </span>
    </div>
    <div>
      <span>month:
      </span> 
      <span id='month'>
      </span>
    </div>
    <div>
      <span>year:
      </span> 
      <span id='year'>
      </span>
    </div>
    <br/>
    <input type="button" id="" value="convert" onClick="convert('/','28/10/1980')"/>
    <span>28/10/1980
    </span>
    <script>
      function convert(delimiter,dateString)
      {
        var splitted = dateString.split('/');
        // create a new date from the splitted string 
        var myDate = new Date(splitted[2],splitted[1],splitted[0]);
        // now you can access the Date and use its methods 
        document.getElementById('day').innerHTML = myDate.getDate();
        document.getElementById('month').innerHTML = myDate.getMonth();
        document.getElementById('year').innerHTML = myDate.getFullYear();
      }
    </script>
  </body>
</html>

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