script.js

function idCard(){
  let firstName = document.getElementById("firstName").value;
  let lastName = document.getElementById("lastName").value;
  let address = document.getElementById("address").value;
  document.getElementById("postFullName").innerHTML = firstName + " " + lastName;
  document.getElementById("postAddress").innerHTML = address;
  
  let age = parseInt(document.getElementById("age").value);
  let phoneNumber = parseInt(document.getElementById("phoneNumber").value);
  
  let numberArray = [];
  numberArray.push(age, phoneNumber);
  
  for (let i = 0; i < numberArray.length; i++){
    if(numberArray[i] <= 100){
      document.getElementById("postAge").innerHTML = "Age: " + age;
    }
    else if(numberArray[i] > 100){
      document.getElementById("postPhoneNumber").innerHTML = "Phone Number: " + phoneNumber;
    }
  }
  
}