sutty-base-jekyll-theme/_packs/controllers/cart_counter_controller.js

import { CartBaseController } from "./cart_base_controller";

export default class extends CartBaseController {
  static targets = ["counter"];

  connect() {
    if (!this.hasCounterTarget) {
      console.error("Missing counter target");
      return;
    }

    window.addEventListener(
      "cart:counter",
      (event) => (this.counter = event.detail.item_count)
    );
    window.addEventListener("storage", (event) => {
      if (event.key == "cart:counter") this.counter = event.newValue;
    });

    if (!this.cart) return;

    this.counter = this.cart.data.attributes.item_count;
  }

  set counter(quantity) {
    this.counterTarget.innerText = quantity;
  }
}