var data = [
{ count: '12', year: '1956' },
{ count: '1', year: '1971' },
{ count: '33', year: '1989' },
{ count: '33', year: '1988' }
];
console.log(data.sort(function (x, y) {
var n = x.count - y.count;
if (n !== 0) {
return n;
}
return x.year - y.year;
}));