You need a simple parsing function like:
function parseDate(s) {
var months = {jan:0,feb:1,mar:2,apr:3,may:4,jun:5,
jul:6,aug:7,sep:8,oct:9,nov:10,dec:11};
var p = s.split('-');
return new Date(p[2], months[p[1].toLowerCase()], p[0]);
}
console.log(parseDate('21-May-2014')); // Wed 21 May 00:00:00 ... 2014