How do I validate a date in this format (yyyy-mm) using js?

Question

I need to validate that a date is in this format (yyyy-mm)
and make sure its before todays date My question is why when I am using this constructor I get one month forward?

new Date(year, month, day, hours, minutes, seconds, milliseconds)

And is this the best approach for such a task? Thank you!

function testDate(dateString){
  dateString = dateString.trim();
  var regEx = /^\d{4}-([0][1-9]|[1][0-2])$/ ;
  if(dateString.match(regEx) !== null){

      var spArr = dateString.split('-');
      var year = parseInt(spArr[0], 10); 
      var month =parseInt(spArr[1], 10); 
      
      var currentDate = new Date();
      inputDate = new Date(year, month, 1, 12, 30, 0, 0);
      alert('year: ' + year + ' month: ' + month);
      alert(inputDate);

      if(inputDate > currentDate){
          alert('Input date ['+dateString+'] is greater than the current date!');
      }
      alert('all ok!');

  }else{
      alert('Input date ['+dateString+'] is of invalid format, correct format: yyyy-MM example: 1975-09');
  }
}

testDate('2014-04                  ');
testDate('14-04');
testDate('2014-4');

[The month is 0-based, not 1-based](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date) — , Mar 26 '19 at 19:48
Don't edit the answer directly into the question. You made your question useless. — , Mar 26 '19 at 19:51
Why would you remove part of your question after you receive an answer? — , Mar 26 '19 at 19:53
because the month was none issue, the approach to solve the problem is the main issue. thank you for your help. — JavaSheriff, Mar 26 '19 at 19:55
Add some Note at last instead of changing original question , if you find some solution from comment — Naga Sai A, Mar 26 '19 at 19:56
Amy, I didn't receive an answer, you just put a comment .... that is why I edited. no big deal question can stay as is. — JavaSheriff, Mar 26 '19 at 20:02

Nino Filiu · Answer 1 · 2019-03-26T20:11:24.430

2

No need to reinvent the wheel. The Date constructor already handles that for you.

const testDate = str => {
  if (/^\d{4}-([0][1-9]|[1][0-2])$/.test(str)===null) return false;
  let now = new Date();
  try {
    return new Date(str)<new Date();
  } catch(err) {
    console.log(err);
    return false;
  }
}

console.log(testDate('2014-04                  '));
console.log(testDate('14-04'));
console.log(testDate('2014-04'));

edited Mar 26 '19 at 20:11

answered Mar 26 '19 at 19:54

Nino Filiu

16,660
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not good because it also accepts this console.log(testDate('2017-01-01')); – JavaSheriff Mar 26 '19 at 20:00
True. Edited for handling this case – Nino Filiu Mar 26 '19 at 20:11
it may not work in all scenarios with new Data('yyyy-mm'), there will be day off – Naga Sai A Mar 26 '19 at 20:33
new Date('2014-04') Mon Mar 31 2014 19:00:00 GMT-0500 (Central Daylight Time) – Naga Sai A Mar 26 '19 at 20:33
https://stackoverflow.com/questions/7556591/is-the-javascript-date-object-always-one-day-off – Naga Sai A Mar 26 '19 at 20:33

How do I validate a date in this format (yyyy-mm) using js?

1 Answers1