I realize that this probably a feature, but I need the Date Constructor to bail on an invalid date not automagically roll it to the appropriate date. What is the best way to accomplish this?
new Date('02/31/2015');
becomes
Tue Mar 03 2015 00:00:00 GMT-0500 (EST)
Sorry if this has already been asked, I wasn't able to/am too stupid to find it :).
It seems that you cannot force a failure on illegal dates. The MDN docs claim, the observed behaviour should only happen when the constructor is called with more than 1 argument, but this condition does not appear to hold (at least it doesn't on chrome 40).
However, you can re-convert the Date and compare it with the original string:
var s = '02/31/2015';
var d = new Date(s)
var s_re = d.toLocaleDateString('en-US', { year: 'numeric', month: '2-digit', day: '2-digit' } );
if (s === s_re) {
// ok
}
If you can count on the string input being formatted as digits (no weekday or month names), you can look at the input before creating a Date object.
function validDate(s){
//check for day-month order:
var ddmm= new Date('12/6/2009').getMonth()=== 5;
//arrange month,day, and year digits:
var A= s.split(/\D+/).slice(0, 3),
month= ddmm? A[1]: A[0],
day= ddmm? A[0]: A[1],
y= A.pop(),
//figure february for given year:
feb= y%4== 0 && (y%100 || y%400== 0)? 29: 28,
// set maximum days per month:
mdays= [0, 31, feb, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];
//if the string is a valid calendar date, return a date object.
//else return NaN (or throw an Error):
return mdays[parseInt(month, 10)]-A[1]>= 0? new Date(s): NaN;
}
validDate('02/29/2015')
/* returned value: (Number) NaN */
I ended up using moment.js. It has validation and overflow calculations among other Date object enhancements. Thanks to Kevin Williams for
You can't set a JavaScript Date object to an invalid date.
Nevertheless you may want to check if a date is invalid.
