var data = [{'start_time':'3a.m','end_time':'4a.m'},{'start_time':'8a.m','end_time':'9a.m'}];
var alertText = "Are you sure you want to select these times?\n"
for(var i in data) {
alertText += data[i].start_time+ " to "+ data[i].end_time +"\n";
}
var response = confirm( alertText );
You can do this. This is show alert as you want.I give you only example using your data.