Class vs. Instance Challenge

you-are-old.js

process.stdin.resume();
process.stdin.setEncoding('ascii');

var input_stdin = "";
var input_stdin_array = "";
var input_currentline = 0;

process.stdin.on('data', function (data) {
    input_stdin += data;
});

process.stdin.on('end', function () {
    input_stdin_array = input_stdin.split("\n");
    main();    
});

function readLine() {
    return input_stdin_array[input_currentline++];
}

function Person(initialAge){
    // Add some more code to run some checks on initialAge
    if (initialAge < 0) {
        initialAge = 0;
        console.log("Age is not valid, setting age to 0.");
    } else if (initialAge > 0) {
        age = initialAge;
      };
  this.amIOld=function(age){
   // Do some computations in here and print out the correct statement to the console
    if (initialAge >=0 && initialAge < 13) {
        console.log("You are young.");
    } else if (initialAge >=13 && initialAge < 18) {
        console.log("You are a teenager.");
    } else if (initialAge >= 18) {
        console.log("You are old.");
    }
  };
   this.yearPasses=function(age){
          // Increment the age of the person in here
       initialAge += 1;
   };
}

function main() {

var T=parseInt(readLine());
for(i=0;i<T;i++){
    var age=parseInt(readLine());
    var p=new Person(age);
    p.amIOld();
    for(j=0;j<3;j++){
        p.yearPasses();
        
    }
    p.amIOld();
    console.log("");   
    }
}