It's not working because you've taken code that uses jQuery, not loaded jQuery in your page, and randomly replaced some, but not all, of the jQuery-specific code with raw Javascript.
Throw that code away and start again from scratch. For example:
document.addEventListener("DOMContentLoaded", () => {
const fields = document.querySelectorAll("#form1 select");
fields.forEach(f => f.addEventListener("change", calculate));
document.querySelectorAll("#form1 option").forEach(o => {
if (o.value !== "0") {
o.innerText += ` - ${o.value}`;
}
});
function calculate() {
let price = 0;
let tArm = 29.95 / 5;
let list = [];
fields.forEach(f => {
const thisValue = +f.value;
if (thisValue !== 0) {
price += thisValue;
price += tArm;
list.push(f.querySelector("option:checked").innerText);
}
});
document.getElementById("list").innerHTML = list.join("<br>")
document.getElementById("price").innerHTML = price.toFixed(2);
const price2 = price / 3;
document.getElementById("price2").innerHTML = price2.toFixed(2);
}
calculate();
});
Demo[
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