diff --git a/includes/class-modal-checkout.php b/includes/class-modal-checkout.php
index 1fe35d05a..1adbfdffd 100644
--- a/includes/class-modal-checkout.php
+++ b/includes/class-modal-checkout.php
@@ -556,7 +556,10 @@ public static function enqueue_scripts() {
 			plugins_url( 'dist/modalCheckout.js', \NEWSPACK_BLOCKS__PLUGIN_FILE ),
 			$dependencies,
 			\NEWSPACK_BLOCKS__VERSION,
-			true
+			[
+				'strategy'  => 'async',
+				'in_footer' => true,
+			]
 		);
 		wp_localize_script(
 			'newspack-blocks-modal-checkout',
@@ -609,7 +612,10 @@ public static function enqueue_modal( $product_id = null ) {
 			plugins_url( 'dist/modal.js', \NEWSPACK_BLOCKS__PLUGIN_FILE ),
 			[],
 			\NEWSPACK_BLOCKS__VERSION,
-			true
+			[
+				'strategy'  => 'async',
+				'in_footer' => true,
+			]
 		);
 		wp_localize_script(
 			'newspack-blocks-modal',
diff --git a/src/modal-checkout/modal.js b/src/modal-checkout/modal.js
index d03c4fb14..462538eeb 100644
--- a/src/modal-checkout/modal.js
+++ b/src/modal-checkout/modal.js
@@ -298,7 +298,7 @@ domReady( () => {
 					form.classList.remove( 'modal-processing' );
 
 					// Set reader activation checkout data if available.
-					let data = {};
+					const data = { is_pending_checkout: true };
 					if ( element.classList.contains( 'wpbnbd--platform-wc' ) ) {
 						const frequency = formData.get( 'donation_frequency' );
 						let amount;
@@ -315,24 +315,17 @@ domReady( () => {
 							layout = 'frequency';
 						}
 
-						data = {
-							type: 'donate',
-							layout,
-							frequency,
-							amount,
-							other: formData.get( `donation_value_${ frequency }_other` ),
-						};
+						data.type = 'donate';
+						data.layout = layout;
+						data.frequency = frequency;
+						data.amount = amount;
+						data.other = formData.get( `donation_value_${ frequency }_other` );
 					} else {
-						data = {
-							type: 'checkout_button',
-							product_id: formData.get( 'product_id' ),
-							variation_id: formData.get( 'variation_id' ),
-						};
+						data.type = 'checkout_button';
+						data.product_id = formData.get( 'product_id' );
+						data.variation_id = formData.get( 'variation_id' );
 					}
-					window?.newspackReaderActivation?.setCheckoutData?.( {
-						is_pending_checkout: true,
-						...data,
-					} );
+					window?.newspackReaderActivation?.setCheckoutData?.( data );
 
 					if (
 						typeof newspack_ras_config !== 'undefined' &&
@@ -414,6 +407,10 @@ domReady( () => {
 						window.newspackReaderActivation.openAuthModal( {
 							title: newspackBlocksModal.labels.auth_modal_title,
 							callback: () => {
+								// Signal checkout registration.
+								form.appendChild(
+									createHiddenInput( newspackBlocksModal.checkout_registration_flag, '1' )
+								);
 								triggerCheckout( form );
 							},
 							skipSuccess: true,
@@ -492,10 +489,6 @@ domReady( () => {
 	 * @param {HTMLFormElement} form The form element.
 	 */
 	const triggerCheckout = form => {
-		// Signal checkout registration.
-		form.appendChild(
-			createHiddenInput( newspackBlocksModal.checkout_registration_flag, '1' )
-		);
 		// form.submit does not trigger submit event listener, so we use requestSubmit.
 		form.requestSubmit( form.querySelector( 'button[type="submit"]' ) );
 	}
diff --git a/src/modal-checkout/utils.js b/src/modal-checkout/utils.js
index 91006edde..85eacea9e 100644
--- a/src/modal-checkout/utils.js
+++ b/src/modal-checkout/utils.js
@@ -7,7 +7,7 @@
  * @return {void}
  */
 export function domReady( callback ) {
-	if ( typeof document === 'undefined' ) {
+	if ( typeof document === 'undefined' || typeof callback !== 'function' ) {
 		return;
 	}
 	if (