SOURCE

// stack
class Stack {
    constructor(){
        this.stack = [];
    }
    push(item){
        this.stack.push(item);
    }
    pop(){
        var item = this.stack.pop();
        return item;
    }
    peek(){
        return this.stack[this.getCount() - 1];
    }
    getCount(){
        return this.stack.length;
    }
    isEmpty(){
        return this.getCount() === 0;
    }
}

let stack = new Stack();
stack.push(10);
stack.push('twenty');
console.log(stack.pop());
console.log(stack.pop());
console.log(stack.isEmpty());

// queue
class Queue {
    constructor(){
        this.queue = [];
    }
    enQueue(item){
        this.queue.push(item);
    }
    deQueue(){
        var item = this.queue.shift();
        return item;
    }
    header(){
        return this.queue[0];
    }
    getCount(){
        return this.queue.length;
    }
    isEmpty(){
        return this.getCount() === 0;
    }
}


//list

class Node {
    constructor(v, next) {
        this.value = v;
        this.next = next;
    }
}

class LinkList {
    constructor(){
        this.size = 0;
        this.dummyNode = new Node(null, null);
    }
    find(header, index, currentIndex){
        if (index == currentIndex) return header;
        return this.find(header.next, index, currentIndex + 1);
    }
    addNode(v, index) {
        this.checkIndex(index);
        let prev = this.find(this.dummyNode, index, 0);
        prev.next = new Node(v, prev.next);
        this.size++;
        return prev.next;
    }
    removeNode(index, isLast) {
        this.checkIndex(index);
        index = isLast ? index - 1 : index;
        let prev = this.find(this.dummyNode, index, 0);
        let node = prev.next;
        prev.next = node.next;
        node.next = null;
        this.size--;
        return node;
    }
    checkIndex(index){
        if (index < 0 || index > this.index) 
            throw Error('Index error');
    }
}