ds-algo-study/DS-n-Algos/Fifo-Lifo/stack_project/lib/stack.js

Just experimenting with publishing a package

// ============================================================================
// Implementation Exercise: Stack
// ============================================================================
//
//
// Implement a Stack and all of its methods below!


class Node {
  constructor(val) {
    this.value = val;
    this.next = null;
  }
}

class Stack {
  constructor() {
    this.top = null;
    this.bottom = null;
    this.length = 0;
  }

  push(val) {
    const newNode = new Node(val);
    if (!this.length) {
      this.bottom = newNode;
      this.top = newNode;
    } else {
      newNode.next = this.top;
      this.top = newNode;
    }
    this.length++;
    return this.length;
  }

  pop() {
    if (!this.length) return null;
    const removedNode = this.top;
    if (this.length === 1) {
      this.top = null;
      this.bottom = null;
    } else {
      this.top = this.top.next;
    }
    this.length--;
    return removedNode.value;
  }

  size() {
    return this.length;
  }
}

exports.Node = Node;
exports.Stack = Stack;