Stack in JS

Introduction

• The stack data structure is a sequential collection of elements that follows the principle of Last In First Out (LIFO).

• The last element inserted into the stack is first element to be removed.

• A stack of plates. The last plate placed on top of the stack is also the first plate removed from the stack.

Operations

• push(element) : add an element to the top

• pop() : remove the top most element

• peek() : get the value of the top element without removing it

• isEmpty() : check if is empty

• size() : get the number of elements

• print() : visualise the elements

Code

class Stack {
  constructor() {
    this.items = [];
  }

  push(item) {
    this.items.push(item);
  }

  pop() {
    return this.items.pop();
  }

  peek() {
    return this.items[this.items.length - 1];
  }

  isEmpty() {
    return this.items.length === 0;
  }

  size() {
    return this.items.length;
  }

  print() {
    console.log(this.items.toString());
  }
}

const stack = new Stack();

console.log(stack.isEmpty()); // true

stack.push(10);
stack.push(20);
stack.push(30);
stack.push(40);
console.log(stack); // { items: [ 10, 20, 30, 40 ] }

console.log(stack.isEmpty()); // false

stack.pop();
console.log(stack); // { items: [ 10, 20, 30 ] }

console.log(stack.peek()); // 30

Usage

• Browser history tracking

• Undo operation when typing

• Expression conversions

• Call stack in JavaScript runtime