Method pop

javascript/0460-lfu-cache.js:23–34

(val)

    }

    pop(val) {
        if (this.map.has(val)) {
            let node = this.map.get(val);

            // save
            let prevNode = node.prev;
            // delete
            prevNode.next = node.next;
            prevNode.next.prev = prevNode;
            this.map.delete(val);
        }
    }

    popleft() {
        let data = this.Left.next.val;