Test Stack in JavaScript – Pop and Peek and Swap returning error

I am trying to practice a stack test in javascript. I am returning what the test is asking for: 46 in the array of storage in the var stackHolder. However, the test result is not showing pop() and peek() functions correctly.

As you can see my consoles match the answer they are expecting, I want to check if I am incorrect or if there is a possible error on the validation to check the answers on their end.

Regarding the swap() – I am asking for a solution that works to get the result they are looking for, which is to swap 1,'{id: 1,value: "obj"}

Here is the code

export function stack( stackOperation, stackValue ) {
var stackHolder = {
count: 4,
storage : [
  1,
  '{id: 1,value: "obj"}',
  "stringHolder",
  46
]
};

var push = function(value) {
stackHolder.storage[stackHolder.count] = value;
return stackHolder.storage;
}

var pop = function() {
if (stackHolder.count === 0) {
  return [];
}

var poppedItem = stackHolder.storage[stackHolder.count];
delete stackHolder.storage[stackHolder.count];
stackHolder.count;

return poppedItem;
}

var peek = function() {
return [stackHolder.storage[0]];
}

var swap = function() {
return stackHolder.storage[1,0];
} 

switch(stackOperation) {
case 'push' : push(stackValue);
return stackHolder.storage;
break;
case 'pop': pop();  
return stackHolder.storage[3];
break;
case 'swap': swap();
return stackHolder.storage;
break;
case 'peek': peek();
return stackHolder.storage[3];
break; 
default:
console.log("DefaultResult", stackHolder.storage);
console.log("POP", stackHolder.storage[3]);
console.log("PEEK", stackHolder.storage[3]);
  return stackHolder.storage;
  }
}

-screen shot of computer validation for answers

–screen shot of console logs

-screen shot of Swap function error