Validation of Bad date in Javascript [duplicate]

Question

I'm following this example to validate date string.

While this below example evaluates to true.

var date = new Date('12/21/2019');
console.log(date instanceof Date && !isNaN(date.valueOf()));

This below example also evaluates to true even though it's a bad date.By bad date I mean, that date does not exist in calendar.

var date = new Date('02/31/2019');
console.log(date instanceof Date && !isNaN(date.valueOf()));

Is there a better way of doing it?

Answer 1

using momentjs

moment("02/30/2019", "MM/DD/YYYY", true).isValid(); // false
moment("03/30/2019", "MM/DD/YYYY", true).isValid(); // true

from current docs of the library here: isValid momentjs

moment("not a real date").isValid(); // false

You can still write your own solution by splitting the string and evaluating for each section. the problem with this approach is that not only February that is not 31 days, there are other months too that are only 30 days. so it will take time before you develop a "not buggy" solution.