Book

class Book{
	
	constructor(title, author, isbn, numCopies){
		
		this.title=title;
		this.author=author;
		this.isbn=isbn;
		this.numCopies=numCopies;
		
	}
	get availability(){
	    return this.getAvailability();
	}
	getAvailability= ()=>{
		if (this.numCopies===0){
		
			return "out of stock";
		
		}
		
		if(this.numCopies<10){
		
			return "low stock";
		
		}
		
		return "in stock";
	}
	
	sell= (numSold=1)=>{
	
		if(numSold<this.numCopies||numSold===this.numCopies){
		
			this.numCopies-=numSold;
		
		}
		
		else{
			if(this.numCopies>0){
				this.numCopies-=1;
			}
		}
		
		
	
	}
	
	restock= (numCopies=5)=>{
		
		this.numCopies+=numCopies;
		return this;
	
	}

}

const HungerGames = new Book("Hunger Games","Suzanne Collins", 123919, 5);
console.log(HungerGames.availability);
HungerGames.restock(120);
console.log(HungerGames.availability);
HungerGames.sell(17);
 console.log(HungerGames.availability);