Check validity before handling submit event in cart

assets/js/frontend/cart.js

@@ -366,9 +366,19 @@ jQuery( function( $ ) {
 
 			// Catch the enter key and don't let it submit the form.
 			if ( 13 === evt.keyCode ) {
+				var $form = $( evt.currentTarget ).parents( 'form' );
+
+				try {
+					// If there are no validation errors, handle the submit.
+					if ( $form[0].checkValidity() ) {
 						evt.preventDefault();
 						this.cart_submit( evt );
 					}
+				} catch( err ) {
+					evt.preventDefault();
+					this.cart_submit( evt );
+				}
+			}
 		},
 
 		/**