Question

Who will answer my question?

How can I validate a date using Javascript cross browser?

I use a invalid date: 2011-11-31 like below:

var d = new Date("2012-11-31")

In FF:

d = NaN // Date is invalid

In Chrome:

d.getFullYear();//2012
d.getDate();//1
d.getMonth();//11

Answer 1

Tested in IE7-9, chrome, opera, safari, firefox. Test here: http://jsfiddle.net/MRwAq/

You could do it like this:

(function(){
                             //This should be good enough initial filter, let the native Date decide if the number are valid
    var validStringRE = /^([0-9]{4})-([0-1][0-9])-([0-3][0-9])$/;

    function pad( num ) {
    return num < 10 ? "0"+num : num;
    }

    Date.prototype.getISOFormat = function(){
    return this.getFullYear() + "-" +
    pad( ( this.getMonth() + 1 ) ) + "-" +
    pad( this.getDate() );
    };

    function isValidISODate( date ) {
    var matches, a;
        if( !validStringRE.test( date.toString() ) ) {
        return false; //Get rid of anything but "NNNN-NN-NN"
        }

    matches = date.match( validStringRE );

    a = new Date( +matches[1], +matches[2] - 1, +matches[3], 0, 0, 0, 0 );

        if( isNaN( a ) ) {
        return false; //firefox, ie
        }

        if( a.toString().toLowerCase() === "invalid date" ) {
        return false; //chrome in some cases, opera, safari
        }

    return a.getISOFormat() === date; //browsers that "conveniently" calculate
    }

window.isValidISODate = isValidISODate;
})()

Then:

var isValid = isValidISODate("2012-11-31");
//false

var isValid = isValidISODate("2012-11-30");
//true