Unable to update Inventory Class

Question

Hello, I have a small code which tries to create a “bag” object, and update the “size” property, but it does not work. The result should be 15, but instead it shows 6. Can anyone give some hints what did I do wrong?? Regards, Ben

class Inventory{
constructor(size){
this.size = size;
}
increase(size){
this.size = size + 1;
}

}

var bag = new Inventory(10);//create bag object with 10 bags
console.log(bag.size); //print initial bag size

bag.increase(5); //increase bag size

console.log(bag.size); //print bag size

https://code.sololearn.com/WlFsqD8Nh95n/?ref=app

Answer 1

Try
this.size += size;

or
this.size = size + this.size;

Answer 2

@Calvin thank you!