11. What is the default value of an ENUM?

If there are no values assigned to Enum, it's values are enumerated from 0.

enum NotAssigned {
	VAL1, VAL2
}

enum Assigned {
	VAL1 = "value1", VAL2 = "value2"
}

console.info(NotAssigned.VAL1, NotAssigned.VAL2); // 0, 1
console.info(Assigned.VAL1, Assigned.VAL2); // value1, value2

console.info(NotAssigned[0], NotAssigned[1]); // VAL1, VAL2
console.info(NotAssigned[NotAssigned.VAL1], NotAssigned[NotAssigned.VAL2]); // VAL1, VAL2

console.info(Assigned[0]); // Property '0' does not exist on type 'typeof Assigned'