Fairly naive JS function for guessing a date from a variety of natural language strings. Includes regexes!

stringToDate.js

function getDateFromString( input ) {
	var d = new Date();
	var this_year = d.getUTCFullYear();

	var date_obj = new Date(input); // try just the default
	if ( _.isDate(date_obj) && _.isFinite(date_obj.getTime()) && date_obj.getUTCFullYear() >= this_year ) { // well that was easy
		return date_obj;
	}

	input_int = _.parseInt(input);
	if ( input_int > this_year && input_int < this_year + 3 ) { // guess we've just got a year numeral
		var date_obj = new Date(input_int, 0, 1);
		if ( _.isDate(date_obj) && _.isFinite(date_obj.getTime()) ) { // whatever we've got is a real date
			return date_obj;
		}
	}

	// we're going to have to get funky to find a date here...
	var months = ['january', 'february', 'march', 'april', 'may', 'june', 'july', 'august', 'september', 'october', 'november', 'december'];
	input = _.trim( input );
	input = _.lowerCase( input );

	// is there a month in the string?
	var match = _.find(months, function (month) {
		return input.match(new RegExp(month.substr(0, 3), 'i'));
	});

	if ( match !== undefined) {
		var month_index = _.indexOf(months, match);

		// get a number we can assume is a day - this will be the first numebr found
		var day_date = input.match(/\d{1,2}/i);
		if ( day_date === null ) {
			// no specific day
			if ( input.match(/begin/i) === null && input.match(/start/i) === null ) {
				//let's assume the end of the month
				day_date = 0;
				month_index += 1;
			}
			else {
				//let's assume the start of the month
				day_date = 1;
			}
		}
		else {
			if ( input.match(/w c/i) !== null ) {
				// end of the specified week
				d = new Date(this_year, month_index, day_date);
				day_date = d.getDate() - d.getDay() + 5;
			}
		}
		return new Date(this_year, month_index, day_date);
	}


	var q_match = input.match(/q (\d{1})/i);
	if ( q_match !== null) {
		month_index = _.parseInt(q_match[1]) * 3; 
		return new Date(this_year, month_index, 0);
	}

	return null;
}