Having trouble with javascript regex for date validation?

Question

Having trouble with javascript regex for date validation?

I am facing an issue with using JavaScript regex to validate date inputs. It is identifying valid dates as invalid, and I'm not sure what the problem is:

/^([0-9]d{2})+(\.|-|\/)+([0-9]d{2})+(\.|-|\/)+([0-9]d{4})+$/

The date formats that should be accepted are:

23/04/2001

23-04-2001

23.04.2001

Initially, I tried this regex pattern but it was accepting dates with extra characters at the end like 23/04/2001jhsdgf:

/\d{2}(\.|-|\/)\d{2}(\.|-|\/)\d{4}/;

javascript regex date validation

Answer 1

Answer №1

To fix your original regex, simply include the ^ and $ from your updated version. Problem solved.

UPDATE: However, it might be better to replace the messy (\.|-|\/) with [.\/-].

UPDATE 2: Another option is to use ([.\/-]) for the first one and then reference it with \1 for the second one, ensuring both separators are the same.

Answer 2

To fix your original regex, simply include the ^ and $ from your updated version. Problem solved.

UPDATE: However, it might be better to replace the messy (\.|-|\/) with [.\/-].

UPDATE 2: Another option is to use ([.\/-]) for the first one and then reference it with \1 for the second one, ensuring both separators are the same.

Answer 3

Answer №2

To verify if a date is correctly formatted, you can utilize a regular expression like the following:

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

^ indicates the start of the string, and $ represents the end
\d{1,2} matches either 1 or 2 digits
\d{4} corresponds to exactly 4 digits
\2 references the separator captured in the second group (- . /)

If a match is found, you can extract the day, month, and year values to construct a new date for comparison. Below is a function that accomplishes this:

function checkDate(dateText) {
    var match = dateText.match(/^(\d{1,2})([-\.\/])(\d{1,2})\2(\d{4})$/);
    // "31.04.2012" -> ["31.04.2012", "31", ".", "04", "2012"]
    if (match === null) {
        return false;
    }
    var date = new Date(+match[4], +match[3] - 1, +match[1]);
    return date.getFullYear() == +match[4] && 
      date.getMonth() == +match[3] - 1 && 
      date.getDate() == +match[1];
}
checkDate("30.04.2013"); // true
checkDate("31-04-2013"); // false (April has 30 days)

The use of + converts strings to numbers (e.g., +"01" becomes 1)
Months are indexed from 0 (0 = January, 1 = February, etc.)
This example assumes the date format as dd-mm-yyyy

The Date object adjusts erroneous dates automatically. For instance, attempting to create 31-4-2013 results in 1-05-2013; the above function validates the resulting date against the input parameters.

Answer 4

To verify if a date is correctly formatted, you can utilize a regular expression like the following:

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

^ indicates the start of the string, and $ represents the end
\d{1,2} matches either 1 or 2 digits
\d{4} corresponds to exactly 4 digits
\2 references the separator captured in the second group (- . /)

If a match is found, you can extract the day, month, and year values to construct a new date for comparison. Below is a function that accomplishes this:

function checkDate(dateText) {
    var match = dateText.match(/^(\d{1,2})([-\.\/])(\d{1,2})\2(\d{4})$/);
    // "31.04.2012" -> ["31.04.2012", "31", ".", "04", "2012"]
    if (match === null) {
        return false;
    }
    var date = new Date(+match[4], +match[3] - 1, +match[1]);
    return date.getFullYear() == +match[4] && 
      date.getMonth() == +match[3] - 1 && 
      date.getDate() == +match[1];
}
checkDate("30.04.2013"); // true
checkDate("31-04-2013"); // false (April has 30 days)

The use of + converts strings to numbers (e.g., +"01" becomes 1)
Months are indexed from 0 (0 = January, 1 = February, etc.)
This example assumes the date format as dd-mm-yyyy

The Date object adjusts erroneous dates automatically. For instance, attempting to create 31-4-2013 results in 1-05-2013; the above function validates the resulting date against the input parameters.

Having trouble with javascript regex for date validation?

Answer №1

Answer №2

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