index-es6-classes-exercise.js

// Implement a stack using ES6 classes:

// Make a array private, Because I want the consumers of the stack to only use push and pop method.
const _items = new WeakMap();

class Stack {
    constructor() {
        _items.set(this, []);
    }

    push(obj) {
        _items.get(this).push(obj);       
    }

    pop() {
        const items = _items.get(this);

        if (items.length === 0)
            throw new Error("Stack is Empty.");
        
        return items.pop();
    }

    peek() {
        const items = _items.get(this);

        if (items.length === 0)
            throw new Error("Stack is Empty.");

        return items[items.length - 1]; 
    }

    get count() {
        return _items.get(this).length;
    }

}


const stack = new Stack();