Question

Format date: MMM D[,] YYYY

[,] – optional comma and may be some space . Example:

Nov 12,     2000 - true
Nov 12 2000 - true
Nov 12, 2000 - true
Nov      12,    2000 true

My regExp:/^(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)\ *(\d{1,2})\,? *(\d{4})$/
But if value – March 2010 all if true

My function for check value

function checkDateWithStringMonth1(value) {
        //reset
        resetDate();
        //set min and max date
        var minYear = 1900;
        //var maxYear = (new Date()).getFullYear();
        // regular expression to match required date format
        re = /^(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)\ *(\d{1,2})\,? *(\d{4})$/;
        //check correct
        if (value != '') {
            if (regs = value.match(re)) {
               if (regs[2] < 1 || regs[2] > 31) {
                    return false;
                }
                if(regs[3] < minYear){return false;}
            } else { return false; }
        } else { return false; }
        //assign

        return true;        
    }

Answer 1

/^(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)\s+(\d{1,2}),?\s+(\d{4})$/

Differences from your original:

• \s instead of [space] to handle different kinds of whitespace
• + instead of *: * means 0 or more, you want 1 or more
• No need to escape ,.

Edit: To accomodate dates with no space after the comma:

/^(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)\s+(\d{1,2})(?:,|\s)\s*(\d{4})$/

• (?: stats a non-capturing group.
• (?:,|\s)\s*: Allow for a comma or a whitespace character, and then possibly more whitespace.

Test:

var dates = ["Nov 12,     2000", "Nov 12 2000", "Nov 12, 2000", "Nov      12,    2000", "Nov 12,2000"],
    regex = /^(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec)\s+(\d{1,2})(?:,|\s)\s*(\d{4})$/;

dates.map(function (d) { return regex.test(d); });
// => [true, true, true, true, true]