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; }
matches = str.match(re);
return new Date(matches[3], months[matches[2]], matches[1]);
}
This function will return the actual date from your date string and then you can compare two dates
customParse("19-Aug-2010") > customParse("18-Aug-2010");