How to extract date from string using javascript

Question

How does one extract a date from a string using javascript? It can be in the following formats:

31.07.2014

07.31.2014

2014.07.31 the same format but divided by spaces or / or - 31 07 2014 31/07/2014 31-07-2014

the string may contain other character like

Teen.Wolf.S04E06.Orphaned.28.07.2014.HDTV

so how to extract date from these type of name.

I thought of first extracting all the numbers and then comparing if it is greater than 12 to make sure it is month or date. I don't know much about regEx (Regular Expressions) so if it is used please explain a little thank you

Answer 1

Maybe this could help you (Demo Fiddle here):

function getDate(d)
{
    var day, month, year;

    result = d.match("[0-9]{2}([\-/ \.])[0-9]{2}[\-/ \.][0-9]{4}");
    if(null != result) {
        dateSplitted = result[0].split(result[1]);
        day = dateSplitted[0];
        month = dateSplitted[1];
        year = dateSplitted[2];
    }
    result = d.match("[0-9]{4}([\-/ \.])[0-9]{2}[\-/ \.][0-9]{2}");
    if(null != result) {
        dateSplitted = result[0].split(result[1]);
        day = dateSplitted[2];
        month = dateSplitted[1];
        year = dateSplitted[0];
    }

    if(month>12) {
        aux = day;
        day = month;
        month = aux;
    }

    return year+"/"+month+"/"+day;
}

Answer 2

probably use a regex like

/(\d{4}([.\-/ ])\d{2}\2\d{2}|\d{2}([.\-/ ])\d{2}\3\d{4})/

\d - a digit (equivilant to character class [0-9]
{n} - match n characters
[.\-/ ] - character class matches a single . - / or space (- needs to be escaped because it indicates a range in a character class
\n - a backreference matches the nth match so / will match another / and not a -, /, space or .

you can pull out the first part of the regex and inspect it, it is the same as the second part, except the 4 digits and 2 digits have been swapped

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