You will need to create a custom parsing function to handle the format you want, and get date objects to compare, for example:

function customParse(str) {

  var months = ['Jan','Feb','Mar','Apr','May','Jun',

                'Jul','Aug','Sep','Oct','Nov','Dec'],

      n = months.length, re = /(d{2})-([a-z]{3})-(d{4})/i, matches;



  while(n--) { months[months[n]]=n; } // map month names to their index :)



  matches = str.match(re); // extract date parts from string



  return new Date(matches[3], months[matches[2]], matches[1]);

}



customParse(18-Aug-2010);

// Wed Aug 18 2010 00:00:00



customParse(19-Aug-2010) > customParse(18-Aug-2010);

// true