Shopify add and remove item from the cart

scripts.js

let cartBtn = document.querySelector("YOUR CART BUTTON CLASS NAME")
const form = document.getElementById("YOUR FORM ID")
form.addEventListener("submit", (e) => {
  e.preventDefault()
  if (cartBtn.getAttribute("data-variant-id")) {
    removeItem()
  }
  else {
    addItem()
  }
})
function removeItem() {
  let variantId = cartBtn.getAttribute("data-variant-id")
  $.ajax({
    type: 'POST',
    url: '/cart/change.js',
    dataType: 'json',
    data: {
      'id': parseFloat(variantId),
      'quantity': 0
    }
  })
    .then(data => {
    cartBtn.textContent = "Add to cart"
    cartBtn.removeAttribute("data-variant-id");
  })
}
function addItem() {
  $.ajax({
    type: 'POST',
    url: '/cart/add.js',
    dataType: 'json',
    data: $('#' + "YOUR FORM ID").serialize()
  })
    .then(data => {
    cartBtn.textContent = "Remove from cart"
    cartBtn.setAttribute("data-variant-id", data.variant_id);
  })
}