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JavaScript

alert(isDate("09/14/2018"));

function isDate(txtDate)

{

  var currVal = txtDate;

  if(currVal == '')

    return false;

   

  //Declare Regex 

  var rxDatePattern = /^(\d{1,2})(\/)(\d{1,2})(\/)(\d{4})$/;

  var dtArray = currVal.match(rxDatePattern); // is format OK?

 

  if (dtArray == null)

     return false;

  

  //Checks for mm/dd/yyyy format.

  dtMonth = dtArray[1];

  dtDay= dtArray[3];

  dtYear = dtArray[5];

 

  if (dtMonth < 1 || dtMonth > 12)

      return false;

  else if (dtDay < 1 || dtDay> 31)

      return false;

  else if ((dtMonth==4 || dtMonth==6 || dtMonth==9 || dtMonth==11) && dtDay ==31)

      return false;

  else if (dtMonth == 2)

  {

     var isleap = (dtYear % 4 == 0 && (dtYear % 100 != 0 || dtYear % 400 == 0));

     if (dtDay> 29 || (dtDay ==29 && !isleap))

          return false;

  }

  return true;

}