Moment js validating edge case, dates like feb 30th [duplicate] - date

Question

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Calculate days to go until a particular date with momentjs
(3 answers)
Closed 1 year ago.
I want to validate if the following date is valid : 30 Feb 2021.
So the main issue is 30 Feb 2021 shouldn't be a valid date or 31 April 2021. is it possible to achieve that with moment js or luxon? or should i use another approach?
let m = moment([2021, 2, 31]);
console.log("Date is valid", m.isValid()); \\returns true which is not a valid date!

Answer 1

I don't know moment.js or luxon , but it's achievable in basic JS (although a little long-winded)
JavaScript will up-tick the date, so the 29th of Feb is the 1st of March.
Therefore we can compare the before and after version :
var month = 1; // zero based - 1 is feb
var day = 30;
var year = 2021;
var testDate = new Date(year, month, day); // will convert to 2nd of March
var parsedDate = testDate.getDate(); // will be 2
var parsedMonth = testdate.getMonth() // will be 2 , zero based, March
var parsedYear = testDate.getFullYear(); // remains 2021 in this case
var isValidDate = parsedDate === day && parsedMonth === month && parsedYear === year;
This could be condensed a lot but I've made it as bloated as possible for readability
you could easily turn it into a function, something like this (untested)
function IsValidDate(year, month, day){
var InputMonthsAreOneBased = 0; // change to 1 if needed
var testDate = new Date(year, month - InputMonthsAreOneBased, day );
return testDate.getDate() === day && testdate.getMonth() === (month - InputMonthsAreOneBased) && testDate.getFullYear() === year;
}