Kassidy Wiskari shrugged her shoulders.

Yes, Harry Potter is all grown up. And yes, J.K. Rowling didn’t write his latest adventure.

No matter.

Wiskari is a die-hard, and when a new installment in the series is released, there are only two things to do:

Stay up until midnight to snag a copy and pull out the Hogwarts uniform from the back of the closet.

“To me, it’s like my entire childhood,” the Naperville junior high student said. “I’m excited to bring all those memories back.”

Downtown Naperville catered to that devotion with a celebration Saturday before “Harry Potter and the Cursed Child” hits the shelves. The eighth book is the script of a two-part play written by Jack Thorne and based off a story he developed with Rowling and director John Tiffany. The stage version premiered in London. But again, fans like Wiskari don’t seem to mind the “Cursed Child” format.

“Well, I’m concerned I don’t get to see the play,” she added.

Naperville businesses and bookstores across the suburbs also treated the release like they did when Rowling’s novels debuted — with a late-night party.

Waving wands in one hand and sipping from butterbeer mugs in the other, Potter enthusiasts packed shops and restaurants that transformed into scenes from the wildly popular series, held costume and trivia contests, and viewed screenings of the movie adaptations.

If you weren’t squinting through your round glasses, you might not have noticed that the instructors of a wizard training camp were really librarians at the downtown Nichols branch.

They taught young students who recited a solemn oath to “honor Harry Potter always” and encouraged kids to jot down a few words about what the boy wizard meant to them on the library’s Muggle Wall.

“Harry Potter inspires me to be brave and creative,” wrote one youngster.

The party, organized by the Downtown Naperville Alliance, culminated at midnight with readers snapping up in-store copies of “Cursed Child” at Barnes & Noble and Anderson’s Bookshop (the library also released books put on hold weeks in advance).

To get a sense of all the offerings, downtown visitors received a seven-page list of activities inspired by the books. Taking a page from the Flourish and Blotts shop in the series, Anderson’s even hosted owls for a live raptor show.

Joyce Sciaky arrived downtown just before 1:30 p.m., hours ahead of the release. But the 13-year-old from Oak Lawn wasn’t counting.

She knew she had plenty to do.

“Anything Harry Potter-related, I love,” she said.