How to throw an error whenever an invalid date object is created?

Question

I raised strange issue:

var d = new Date("2016--01---01");

Would create object without any errors. Actually, first question is - why?

But then i need to get string from this object - i am trying to

d.toString();     // 'Invalid Date'
d.getTime();      // NaN
d.toJSON();       // null

What it is possible ways to get string or check that it is incorrect?

do you want check whether the provided string is vaild date or not ? — murli2308, Mar 23 '16 at 12:16
Do you want to check that the string is valid before creating the `Date()`, or that the `Date()` is invalid afterwards? — jonny, Mar 23 '16 at 12:16
i need to get error on creating or actual wrong date from `Date` object — alexey, Mar 23 '16 at 12:17

score 1 · Answer 1 · answered Mar 23 '16 at 12:16

You can simply check it's a valid number when converted to one:

var ok = !isNaN(d);

(this conversion is the same than taking d.getTime()).

But be warned that a valid date might be not the desired date. You usually use a verified date format. Libraries like moment.js might help you on that.

score 1 · Answer 2 · answered Mar 23 '16 at 12:22

Create a factory type function which throws an error if the string given produces an invalid date, but returns the date if it's valid

var d = createDate("2016--01---01")

createDate = function(str) {    
  var date = new Date(str)
  if(date instanceof Date && !isNaN(date.valueOf())) return date
  else throw Error('invalid date')
}

How to throw an error whenever an invalid date object is created?

2 Answers2