Ok, the undefined error because of the key naming, the key name is "DTSTART;TZID=America/New_York" and not "DTSTART". Based on the circumstances you describe, here is an alternative to access the array value using key like/startsWith. Now, your next assignment is to figure out how to display the result in the order that you prefer because the loop start from top to bottom.
for (var i = 0; i < myObj.cars.length; i++){
var obj = myObj.cars[i];
for (var key in obj){
if (key == "SUMMARY") {
x += "<h1>" + obj[key] + "</h1>";
}
if (key.startsWith("DTSTART")) {
x += "<h2>" + obj[key] + "</h2>";
}
}
}
Output:
20170211T123000
monday meeting