How to check if string is valid date or not?

Sanjay Makwana

5y1.4kWeb Development

I want to check if the string is a valid date or not.

Date.parse() is not working in this case, because if I pass a string in Date.parse(), it is returning a number.

8 Replies

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Sachin Singh5y ago
yes, you are right, then I think regex is the option
function checkIfValidDate(str) {

  const regexExp = /(?:(?:31(\/|-|\.)(?:0?[13578]|1[02]))\1|(?:(?:29|30)(\/|-|\.)(?:0?[13-9]|1[0-2])\2))(?:(?:1[6-9]|[2-9]\d)?\d{2})$|^(?:29(\/|-|\.)0?2\3(?:(?:(?:1[6-9]|[2-9]\d)?(?:0[48]|[2468][048]|[13579][26])|(?:(?:16|[2468][048]|[3579][26])00))))$|^(?:0?[1-9]|1\d|2[0-8])(\/|-|\.)(?:(?:0?[1-9])|(?:1[0-2]))\4(?:(?:1[6-9]|[2-9]\d)?\d{2})/gi;

  return regexExp.test(str);
}

// Use the function
checkIfValidDate("01-01-2021"); // true
checkIfValidDate("32-01-2021"); // false
+3
Sanjay Makwana5y ago
Even if I use isNaN, it is not working. When you use "abcd" it will give right result, but try with the value I am using, it will not work.

+1
Sachin Singh5y ago
you haven't use isNaN(), make sure to use it as well.

+4
Sanjay Makwana5y ago
This code will return results even if we use string.

+1
Sachin Singh5y ago
for javascript use this
function IsValidDate(dateString) {
  return !isNaN(new Date(dateString).getDate());
}
+2
Sanjay Makwana5y ago
Thanks for reply.

I want this in Javascript.
+1
Basem Alshabani5y ago
Use Tryparse method of DateTime class
+1
Sachin Singh5y ago
Use TryParse or TryParseExact.
If you have to check against a valid date format then use this
string format = "ddd dd MMM h:mm tt yyyy";
DateTime dateTime;
if (DateTime.TryParseExact(dateString, format, CultureInfo.InvariantCulture,
    DateTimeStyles.None, out dateTime))
{
    Console.WriteLine(dateTime);
}
else
{
    Console.WriteLine("Not a date");
}
without format use this
DateTime mydate;
if (DateTime.TryParse(dateString, out mydate) == true)
{
     //do any thing with mydate
}
+2