Javascript正则表达式以验证日期

Question

I am rather unfamiliar with regular expressions. I am trying to write a regular expression for mm.dd.yyyy, mm/dd/yyyy or mm-dd-yyyy. This is what I have so far, I am completely unsure if I am even close.

^[0-9]{4}-(((0[13578]|(10|12))-(0[1-9]|[1-2][0-9]|3[0-1]))|(02-(0[1-9]|[1-2][0-9]))|((0[469]|11)-(0[1-9]|[1-2][0-9]|30)))$

Thanks

Answer 1

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

jsFiddle .

Note that this will allow them to be mixed up, ie 01/02-2010 would be valid. To stop this, write it out three times like so...

/^(?:\d{2}\.\d{2}\.\d{4}|\d{2}\/\d{2}\/\d{4}|\d{2}-\d{2}-\d{4})$/

jsFiddle .

(or just check cwolves's wonderful answer .)

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Your question title says...

Javascript Regular Expression to validate date

If you also need to extract the portions, wrap them with parenthesis ( () ) which will turn them into capturing groups. They will be stored in members of the returned array if a successful match.

Answer 2

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

will match 01/01/2000 , 01.01.2000 , NOT 01/01.2000

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

does the same while wrapping the three date parts.

Answer 3

I have seen some monster regular expressions to match actual dates- they would not match 04/31/yyyy, for instance, or 02-29-2011.

It is simpler to try to make a date from the input, and then check the input.

function isvalid_mdy(s){
    var day, A= s.split(/\D+/).map(function(itm){
        return parseInt(itm, 10)
    });
    try{
        day= new Date(A[2], A[0]-1, A[1]);
        if(day.getMonth()+1== A[0] && day.getDate()== A[1]) return day;
        throw 'Bad Date Format';
    }
    catch(er){
        return NaN;
    }

}

var s1= '04/31/2011';
isvalid_mdy(s1)

/*  returned value: (Number)
NaN

*/

Answer 4

In PHP I use named matches, so different formats are easy:

$format = 'y-m-d'; // or 'd-m-y' or 'd/m/y' etc
$regexp = '#^'.strtr(preg_quote($format), array('y' => '(?P<year>(?:1|2)\d{3})', 'm' => '(?P<month>\d\d?)', 'd' => '(?P<day>\d\d?)')).'$#';

but I don't think it's possible like that in JS. Maybe named matches some other way...

edit
I tried this:

'2004-8-29'.match(/^(\3\d{4})-(\2\d\d?)-(\1\d\d?)$/)

but I don't think that's it... (Notice the \\3, \\2 and \\1 before the actual captures/matches)

In order 1, 2, 3, it matches. In order 3, 2, 1, it doesn't. Not sure what the \\1 , \\2 and \\3 do =)

Answer 5

I don't like repeating the patterns once each for . , - and /

Try something like the below:

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

Note the use of \\2 representing the second matching group which is the group of . , - or / . This will make sure that whatever symbol was between mm and dd will be matched between dd and yyyy.

Answer 6

An interesting trick is that you can use Date.parse() to do something along those lines:

// 1303617600000
Date.parse('4/24/2011')

// 1303617600000
Date.parse('4-24-2011')

// 1303617600000
Date.parse('4.24.2011')

// NaN
Date.parse('4/32/2011')

// NaN
Date.parse('foo')

It's not perfectly strict. For example, it will successfully parse 2/30/2011 as valid. It's a good 99%-strict sanity test though.