Initial line item idea

assets/javascripts/nested_form_controller.js

@@ -0,0 +1,19 @@
+(function() {
+  class NestedFormController extends Stimulus.Controller {
+    static targets = ["container", "template"]
+
+    add(event) {
+      event.preventDefault();
+      const content = this.templateTarget.innerHTML.replace(/NEW_RECORD/g, new Date().getTime());
+      this.containerTarget.insertAdjacentHTML("beforeend", content);
+    }
+
+    remove(event) {
+      event.preventDefault();
+      event.target.closest(".nested-fields").remove();
+    }
+  }
+
+  // Expose globally so index.js can access it
+  window.NestedFormController = NestedFormController;
+})();