Picture this. You’re getting ready to go to your senior

, and you’re on cloud nine because you know you’ve picked the perfect dress. Then you arrive at the dance only to discover that someone else is wearing the same outfit you are.

“It ruins the night,” said Alexandra Wenger, 18, a senior at Cedar Cliff High School.

Indeed, the idea haunted Wenger so much that she decided to take matters into her own hands. The result?

.

The new website, which Wenger did as her school senior project, attempts to prevent such a fashion mishap by having students post pictures of their dresses online. “My mom and I have gone dress shopping every year,” she said. “And in the dressing room I always turn and say ‘I hope no one else has this dress too.’ Finally last year I decided to do something about it.”

The basic concept is simple. Girls who create an account on the site (registration is free) get access to a “closet,” where they can upload photos of their new dress and then enter the name of the prom or other event they plan to wear said gown at.

The idea is that girls heading to the same event will go to the site and by looking at the other girls’ “closets,” manage to avoid purchasing the same or a similar dress.

The site also lets users share their worst “oh no” prom moments, post group pictures of their friends, follow links to local stores (users can recommend stores as well), and discover places to buy accessories like shoes and purses.

Wenger worked with designer firms M Street Associates in Strasburg and 206 Design in Mechanicsburg to help put the site together, which included figuring out the logo, deciding what colors to use, and, of course, what exactly the site’s content should include. “There was definitely a lot going into the thought process and planning,” she said.

Ultimately, she hopes the site will “explode and ... every girl in the nation [will] use and enjoy it.”

While registration is free, Wenger hopes the site will bring in revenue from advertising — the site just became part of Zappos.com’s Associates ad program — with the money not only going toward the site’s maintenance, but also helping to pay her college tuition.

Wenger will be attending Penn State in the fall, where she’s leaning toward a major in marketing and business.