How to Write Regex to Validate Dates

Regex to validate date formats dd/mm/YYYY, dd-mm-YYYY, dd.mm.YYYY, dd mmm YYYY, dd-mmm-YYYY, dd/mmm/YYYY, dd.mmm.YYYY with Leap Year Support

The regex you pasted does not validate leap years correctly, but there is one that does in the same post.
I modified it to take dd/mm/yyyy, dd-mm-yyyy or dd.mm.yyyy.

^(?:(?:31(\/|-|\.)(?:0?[13578]|1[02]))\1|(?:(?:29|30)(\/|-|\.)(?:0?[13-9]|1[0-2])\2))(?:(?:1[6-9]|[2-9]\d)?\d{2})$|^(?:29(\/|-|\.)0?2\3(?:(?:(?:1[6-9]|[2-9]\d)?(?:0[48]|[2468][048]|[13579][26])|(?:(?:16|[2468][048]|[3579][26])00))))$|^(?:0?[1-9]|1\d|2[0-8])(\/|-|\.)(?:(?:0?[1-9])|(?:1[0-2]))\4(?:(?:1[6-9]|[2-9]\d)?\d{2})$

I tested it a bit in the link Arun provided in his answer and also here and it seems to work.

Edit February 14th 2019: I've removed a comma that was in the regex which allowed dates like 29-0,-11

Regex to match date formats DD-MM-YYYY and DD/MM/YYYY

This pattern will work for your conditon. Strictly not allowed month to date and vice versa.

^([0]?[1-9]|[1|2][0-9]|[3][0|1])[./-]([0]?[1-9]|[1][0-2])[./-]([0-9]{4}|[0-9]{2})$

This pattern will match these formats: (Date, Month, Year)

Regex to validate date format

For a month from 1-12 adding a zero for a single digit 1-9:

(?:0[1-9]|1[012])

For a day 1-31 adding a zero for a single digit 1-9:

(?:0[1-9]|[12]\d|3[01])

Putting it all together with 4 digits to match a year (note that \d{4} can also match 0000 and 9999), enclosed in word boundaries \b to prevent a partial match with leading or trailing digits / word characters:

\b\d{4}(?:0[1-9]|1[012])(?:0[1-9]|[12]\d|3[01])\b

A variation, limiting the scope for a year to for example 1900 - 2099

\b(?:19|20)\d{2}(?:0[1-9]|1[012])(?:0[1-9]|[12]\d|3[01])\b

But note that this does not validate the date itself, it can for example also match 20210231. To validate a date, use a designated api for handling a date in the tool or code.

How to write regex to validate dates?

I came up with this:

function isValidDate(inputDate){

    var myRegex = /^(\d{1,2})([\-\/])(\d{1,2})\2(\d{4}|\d{2})$/;
    var match = myRegex.exec(inputDate);

    if (match != null) {
        var auxDay = match[1];
        var auxMonth = match[3] - 1;
        var auxYear = match[4];
        auxYear = auxYear.length < 3 ? (auxYear < 70 ? '20' + auxYear : '19' + auxYear) : auxYear;
        var testingDate = new Date(auxYear,auxMonth,auxDay);
        return ((auxDay == testingDate.getDate()) && (auxMonth == testingDate.getMonth()) && (auxYear == testingDate.getFullYear()));
    } else return false;
}

Works for dd-mm-yyyy, dd-mm-yy, d-m-yyyy and d-m-yy, using - or / as separators

Based on This script

Javascript - Regex to validate date format

You could use a character class ([./-]) so that the seperators can be any of the defined characters

var dateReg = /^\d{2}[./-]\d{2}[./-]\d{4}$/

Or better still, match the character class for the first seperator, then capture that as a group ([./-]) and use a reference to the captured group \1 to match the second seperator, which will ensure that both seperators are the same:

var dateReg = /^\d{2}([./-])\d{2}\1\d{4}$/

"22-03-1981".match(dateReg) // matches
"22.03-1981".match(dateReg) // does not match
"22.03.1981".match(dateReg) // matches

Date of birth validation by using regular expression

For regex for dates, see the link: Regex Tutorial

But I think the example will work.

  "^(0[1-9]|1[012])[-/.](0[1-9]|[12][0-9]|3[01])[-/.](19|20)\\d\\d$"

Regular Expression to match valid dates

This is not an appropriate use of regular expressions. You'd be better off using

[0-9]{2}/[0-9]{2}/[0-9]{4}

and then checking ranges in a higher-level language.

regular expression to validate datetime format (MM/DD/YYYY)

Try your regex with a tool like http://jsregex.com/ (There is many) or better, a unit test.

For a native validation:

function validateDate(testdate) {
    var date_regex = /^\d{2}\/\d{2}\/\d{4}$/ ;
    return date_regex.test(testdate);
}

In your case, to validate (MM/DD/YYYY), with a year between 1900 and 2099, I'll write it like that:

function validateDate(testdate) {
    var date_regex = /^(0[1-9]|1[0-2])\/(0[1-9]|1\d|2\d|3[01])\/(19|20)\d{2}$/ ;
    return date_regex.test(testdate);
}

Date validation with regular expression

You can select 1 or 2 digit occurrences with \d{1,2}.
There are missing square brackets in the last hypen / forward slash group.
And the last group should be (\d{2}|\d{4}).
No need to escape the forward slash inside the character classes.
```
/^(\d{1,2})([\-/])(\d{1,2})([\-/])(\d{2}|\d{4})$/
```