Simple Parse Date In Javascript

gistfile1.txt

function parseDate(str) {
  var parts = str.split( /\s|,|-|\// );
  var isNum  = function(val) { return !isNaN( parseFloat( val ) ) && isFinite( val ); };
  var isYear = function(val) { return 4 === val.length && isNum(val); };
  var yIndex = null;
  var mIndex = null;
  var dIndex = null;
  var rtDate = null;

  if ( parts.length === 2 ) {
    if ( isYear( parts[ 0 ] ) ) {
      yIndex = 0;
      mIndex = 1;
    }
    else if( isYear( parts[ 1 ] )) {
      yIndex = 1;
      mIndex = 0;
    }
  } else if(parts.length === 3) {
    if ( isYear( parts[ 0 ] ) ) {
      yIndex = 0;
      mIndex = 1;
      dIndex = 2;
    } else if ( isYear( parts[ 2 ] ) ) {
      yIndex = 2;
      mIndex = 0;
      dIndex = 1;
    }
  }

  var map = { jan: 1, feb: 2, mar: 3, apr: 4, may: 5, jun: 6, jul: 7, aug: 8, sep: 9, oct: 10, nov: 11, dec: 12 };
  var month = isNum(parts[mIndex]) ? parts[mIndex] : map[parts[mIndex].substr(0,3).toLowerCase()] || null;
  var day = null !== dIndex ? parts[dIndex] || null : 1;
  var year = null !== yIndex ? parts[yIndex] || null : null;
  if ( month && day && year ) {
    rtDate = new Date( year, month - 1, day, 0, 0, 0 );
  }

  return null !== rtDate && !isNaN(rtDate.getMonth()) ? rtDate : null;
}