This site is mobile accessible. Press the "Tap Here" button to use a smaller font-size.

Tap Here!

Smartphone icons created by Freepik - Flaticon

JS Classes uses "strict mode"

In a JavaScript Class you cannot use variable without declaring it.

class Car {
  constructor(name, year) {
    this.name = name;
    this.year = year;

  }
  age() {
   // date = new Date();  // This will not work
   const date = new Date(); // This will work
   return date.getFullYear() - this.year;
  }
}

const myCar = new Car("Ford", 2014);
document.getElementById("demo").innerHTML =
"My car is " + myCar.age() + " years old.";