var maxSpeed = {
car: 300,
bike: 60,
motorbike: 200,
airplane: 1000,
helicopter: 400,
rocket: 8 * 60 * 60
};
var sortable = [];
for (var vehicle in maxSpeed) {
sortable.push([vehicle, maxSpeed[vehicle]]);
}
sortable.sort(function(a, b) {
return a[1] - b[1];
});
//[["bike", 60], ["motorbike", 200], ["car", 300],
//["helicopter", 400], ["airplane", 1000], ["rocket", 28800]]