Stack: Array as Storage

Before writing this, I had a serious debate with myself. Is there a need to implement your own stack using arrays in JavaScript, when the the language itself provides methods, pop() and push(), which are needed in a typical stack???

For the sake of understanding stacks better, I ended up implementing my own, assuming that my stack grows dynamically.

Implementation

1.Create a stack class

class Stack { constructor() { this.items = []; this.size = -1; } //add methods } 

In our stack class, we declare an array to implement a stack and set the size to -1 (empty).

2.Add methods to stack class to perform push, pop, peek.

push item to stack

push(data) { //if an item is provided if (data) { //add item to array this.items.push(data); //increase size this.size++; } return; } 

Here, an item is added to top of stack.

pop item in stack
The top item in stack is removed and returned. If list is empty Underflow is returned.

pop() { //if empty if (this.size === -1) { return "UnderFlow"; } else { this.size--; //return top item in stack return this.items.pop(); } } 

peek
Returns top element but does not remove it from stack

 peek() { //if empty if (this.size === -1) { return "Empty stack"; } //return top item in stack return this.items[this.size]; } 

Example Test Code

let stack = new Stack(); stack.push(3); stack.push(5); stack.push(7); console.log(stack.pop());//7 console.log(stack.peek());//5 console.log(stack)//[3, 5] 

Next, I'll be applying my stack knowledge in creating a postfix calculator 😉 .
Happy coding.