Question

I need to validate a primitive date of birth field input in the format of:

‘mmmyyyy’

Where the first 3 characters of the string must be an acceptable 3-letter abbreviation of the months of the year.
It can be lowercase, or uppercase, or a mix of any so long as it spells out jan or feb or mar etc etc etc.
There is no built-in method that I am aware of that has a ready array of this specific format of a month to be able compare against user input. I was thinking that I could maybe use the localeCompare() method in a for loop to test if the output is not 0 then append an error message accordingly.

Answer 1

function dateTester() {
   var d = new Date(),
      i,
      mo = [],
      moIsValid;
   for (i = 0; i < 12; i += 1) {
      d.setMonth(i);
      mo.push(d.toLocaleString().split(' ')[1].substr(0, 3));
   }
   return new RegExp('^(' + mo.join('|') + ')', 'i');
}

var moIsValid = dateTester();
alert(moIsValid.test('fEb1992'));

If you don’t want the user’s current locale name for the days to be valid, then just switch toLocaleString() to toString(). But then, why don’t you just do this instead:

var moIsValid = /^(jan|feb|mar|apr|may|jun|jul|aug|sep|oct|nov|dec)/i;
alert(moIsValid.test('fEb1992'));