This piece of js code is supposed to implement a stack using a list $($NOT AN ARRAY$).$ It is supposed to only allow integers and operands. When an integer is entered it pushes it to the stack. if an operand is entered $(+,-,*,/)$ it does an equation using the previous two inputed integers. My code keeps randomly returning a $0$ while I$\text{'}$m inputting integers how do I fix? $//$ Node class

class Node $\{$

constructor$($data$)\{$

this.data $=$ data;

this.next $=$ null;

$\}$

$\}$

$//$ Stack class

class Stack $\{$

constructor$()\{$

this.top $=$ null;

this.size $=0$;

$\}$

$//$ Push operation

push$($data$)\{$

$//$ Create a new node with the data

let node $=$ new Node$($data$)$;

$//$ If the stack is empty, set the node as the top node

if $($this$.$isEmpty$())\{$

this.top $=$ node;

$\}$ else $\{$

$//$ If the stack is not empty, set the node as the next of the top node

node.next $=$ this.top;

$//$ Set the node as the new top node

this.top $=$ node;

$\}$

$//$ Increment the size of the stack

this.size$++$;

$\}$

$//$ Pop operation

pop$()\{$

$//$ If the stack is empty, return null

if $($this$.$isEmpty$())\{$

return null;

$\}$ else $\{$

$//$ If the stack is not empty, get the data of the top node

let data $=$ this.top.data;

$//$ Set the next node as the new top node

this.top $=$ this.top.next;

$//$ Decrement the size of the stack

this.size$--$;

$//$ Return the data

return data;

$\}$

$\}$

$//$ Show operation

show$()\{$

$//$ Initialize an empty array to store the data

let items $=[]$;

$//$ Initialize a current node as the top node

let current $=$ this.top;

$//$ Loop through the stack until the current node is null

while $($current$)\{$

$//$ Push the data of the current node to the array

items.push$($current$.$data$)$;

$//$ Set the current node as the next node

current $=$ current.next;

$\}$

$//$ Return the array

return items;

$\}$

$//$ Clear operation

clear$()\{$

$//$ Set the top node as null

this.top $=$ null;

$//$ Set the size as zero

this.size $=0$;

$\}$

$//$ Count operation

count$()\{$

$//$ Return the size of the stack

return this.size;

$\}$

$//$ Peek operation

peek$()\{$

$//$ If the stack is empty, return null

if $($this$.$isEmpty$())\{$

return null;

$\}$ else $\{$

$//$ If the stack is not empty, return the data of the top node

return this.top.data;

$\}$

$\}$

$//$ IsEmpty operation

isEmpty$()\{$

$//$ Return true if the size is zero, false otherwise

return this.size $===0$;

$\}$

$\}$

let stack $=$ new Stack$()$;

$//$ Calculator function

function btnClick$()\{$

$//$ Function to read input data and perform operation

$//$ Getting input data

let input $=$ document.getElementById$("$input$").$value;

let buttons $=$ document.querySelectorAll$("$button$")$;

for $($let button of buttons$)\{$

button.addEventListener$("$click$",$ btnClick$)$;

$\}$

$//$ Checks for number

if $($isNaN$($input$)==$ false$)\{$

$//$ Converting to number from string

input $=$ Number$($input$)$;

$//$ Pushing to stack

stack.push$($input$)$;

document.getElementById$("$msg$").$innerHTML $=$ input $+"$ Added to stack";

console.log$($input $+"$ Added to stack"$)$;

$\}$ else $\{$

$//$ Check for operator

if $($stack$.$count$()>1)\{$

$//$ If stack has more than one elements

if $($input $=="+"||$ input $=="-"||$ input $=="/"||$ input $=="*"||$ input $=="\%")\{$

$//$ If valid operator given

$//$ Popping operands

let y $=$ stack.pop$()$;

let x $=$ stack.pop$()$;

$//$ Calculating result

let result $=$ doMath$($x$,$ y$,$ input$)$;

$//$ Pushing result to stack

stack.push$($result$)$;

document.getElementById$("$msg$").$innerHTML $=$ "Result: $"+$ result;

console.log$("$valid operator"$)$;

console.log$("$Result:$"+$ result$)$;

$\}$ else $\{$

$//$ Message for invalid operator

console.log$("$Invalid operator"$)$;

document.getElementById$("$msg$").$innerHTML $=$ "Invalid operator$($try: $+,-,*,/,\%)"$;

$\}$

$\}$ else $\{$

$//$ Message for few operands

document.getElementById$("$msg$").$innerHTML $=$ "Not much value to perform task";

console.log$("$Not much value to perform task"$)$;

$\}$

$\}$

document.getElementById$("$input$").$value $=""$;

$\}$

$//$ Function to perform operation

function doMath$($x$,$ y$,$ o$)\{$

switch $($o$)\{$

case $"+"$:

return x $+$ y;

case $"-"$:

return x $-$ y;

case $"*"$:

return x $*$ y;

case $"/"$:

return x $/$ y;

case $"\%"$:

return x $\%$ y;

$\}$

$\}$