Added PersonModel; revised XOR 

Overly excited about my first use of a ternary operator. That's some cool stuff.
Great job.  If your person has an age of 0 this returns false. I think that's what we want I just want to make sure it's what you meant.  0 equates to false in javaScript so a person with an age of 0 is being passed through the first part of your logic as true since 0 is greater than -1 and less than 116 and then returning false on the second part. If you wanted an age of 0 to return true for isAlive you could just increase the first part to this.age > 0.  Just wanted to make sure you were aware of what was going on here. If you were, good on ya!