A simple queue

Similar to a stack, we will create a queue using the following steps:

1. Define a constructor():

class Queue {
    constructor() {
    
    }
}

1. We will be using WeakMap() for in-memory data storage just like we did for stacks: 

    const qKey = {};
    const items = new WeakMap();

    class Queue {
        constructor() {
            
        }
    }

1. Implement the methods described previously in the API:

var Queue = (() => {
    const qKey = {};
    const items = new WeakMap();

    class Queue {

        constructor() {
            items.set(qKey, []);
        }

        add(element) {
            let queue = items.get(qKey);
            queue.push(element);
        }

        remove() {
            let queue = items.get(qKey);
            return queue.shift();
        }

        peek() {
            let queue = items.get(qKey);
            return queue[queue.length - 1];
        }

        front() {
            let queue = items.get(qKey);
            return queue[0];
        }

        clear() {
            items.set(qKey, []);
        }

        size() {
            return items.get(qKey).length;
        }
    }

    return Queue;
})();

We have again wrapped the entire class inside an IIFE because we don't want to make ;Queue items accessible from the outside: