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Check if a string is a date value


Question

What is an easy way to check if a value is a valid date, any known date format allowed.

For example I have the values 10-11-2009, 10/11/2009, 2009-11-10T07:00:00+0000 which should all be recognized as date values, and the values 200, 10, 350, which should not be recognized as a date value. What is the simplest way to check this, if this is even possible? Because timestamps would also be allowed.

2016/08/01
1
214
8/1/2016 8:44:37 AM

Accepted Answer

Would Date.parse() suffice?

See its relative MDN Documentation page.

2016/01/12
43
1/12/2016 11:55:28 PM


This is how I solved this problem in an app I'm working on right now:

updated based on feedback from krillgar:

var isDate = function(date) {
    return (new Date(date) !== "Invalid Date") && !isNaN(new Date(date));
}
2020/06/05

new Date(date) === 'Invalid Date' only works in Firefox and Chrome. IE8 (the one I have on my machine for testing purposes) gives NaN.

As was stated to the accepted answer, Date.parse(date) will also work for numbers. So to get around that, you could also check that it is not a number (if that's something you want to confirm).

var parsedDate = Date.parse(date);

// You want to check again for !isNaN(parsedDate) here because Dates can be converted
// to numbers, but a failed Date parse will not.
if (isNaN(date) && !isNaN(parsedDate)) {
    /* do your work */
}
2016/08/17

How about something like this? It will test if it is a Date object or a date string:

function isDate(value) {
    var dateFormat;
    if (toString.call(value) === '[object Date]') {
        return true;
    }
    if (typeof value.replace === 'function') {
        value.replace(/^\s+|\s+$/gm, '');
    }
    dateFormat = /(^\d{1,4}[\.|\\/|-]\d{1,2}[\.|\\/|-]\d{1,4})(\s*(?:0?[1-9]:[0-5]|1(?=[012])\d:[0-5])\d\s*[ap]m)?$/;
    return dateFormat.test(value);
}

I should mention that this doesn't test for ISO formatted strings but with a little more work to the RegExp you should be good.

2018/12/19

None of the answers here address checking whether the date is invalid such as February 31. This function addresses that by checking if the returned month is equivalent to the original month and making sure a valid year was presented.

//expected input dd/mm/yyyy or dd.mm.yyyy or dd-mm-yyyy
function isValidDate(s) {
  var separators = ['\\.', '\\-', '\\/'];
  var bits = s.split(new RegExp(separators.join('|'), 'g'));
  var d = new Date(bits[2], bits[1] - 1, bits[0]);
  return d.getFullYear() == bits[2] && d.getMonth() + 1 == bits[1];
} 

Use Regular expression to validate it.

isDate('2018-08-01T18:30:00.000Z');

isDate(_date){
        const _regExp  = new RegExp('^(-?(?:[1-9][0-9]*)?[0-9]{4})-(1[0-2]|0[1-9])-(3[01]|0[1-9]|[12][0-9])T(2[0-3]|[01][0-9]):([0-5][0-9]):([0-5][0-9])(.[0-9]+)?(Z)?$');
        return _regExp.test(_date);
    }
2018/10/31

Source: https://stackoverflow.com/questions/7445328
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