if$($document$.$readyState $===$ 'loading'$)\{$

document.addEventListener$(\text{'}$DOMContentLoaded$\text{'},$ showItems$)$;

$\}$ else$\{$

showItems$()$;

$\}$

function showItems$()\{$

const backPrice $=$ document.getElementsByClassName$("$price$")$;

const calcPrice $=$ document.getElementsByClassName$("$price$")$;

const textPrice $=$ document.getElementsByClassName$("$price$")$;

const backpackPrice $=$ backPrice.textContent;

const calculatorPrice $=$ calcPrice.textContent;

const textbookPrice $=$ textPrice.textContent;

const prices $=[$Number$("$backPackPrice$"),$Number$($calculatorPrice$),$Number$($textPrice$)]$;

return prices;

$\}$

function pricesAdd$($prices$)\{$

let sum $=0$;

for $($let i $=0$; i $<$ prices.length; i$++)\{$

sum $+=$ Number$($prices$[$i$])$;

$\}$

return sum;

$\}$

function calcSum$()\{$

const prices $=$ showItems;

const subTotal $=$ pricesAdd$($prices$)$;

return subTotal;

$\}$

function taxRate$()\{$

const taxRate $=0\mathrm{.}13$;

return taxRate;

$\}$

function calcTax$($sum$)\{$

let taxAmount $=0$;

const rate $=$ taxRate$()$;

taxAmount $=$ sum $*$ rate;

return taxAmount;

$\}$

function calcFinalCost$($sum$,$ tax$)\{$

const finalCostAmount $=$ sum $+$ tax;

document.getElementById$("$sub$-$total"$).$textContent $=$ sum.toFixed$(2)$;

document.getElementById$("$tax$-$amount"$).$textContent $=$ tax.toFixed$(2)$;

document.getElementById$("$total$").$textContent $=$ finalCostAmount.toFixed$(2)$;

$\}$

$($function$()\{$

const sum $=$ calcSum$()$;

const tax $=$ calcTax$($sum$)$;

calcFinalCost$($sum$,$ tax$)$;

$\})()$;

Can you fix code with proper way of using getElementbyClassName

Also correct what needs to be corrected to not bring up errors