These days Joan Rivers can say anything, and does

“Who knows what can be considered dirty when there are no boundaries?” says Joan Rivers, who will perform at the Wilbur Theatre on Saturday.Trae Patton/Bravo/file/© Bravo

Even the briefest survey of Joan Rivers’s Twitter feed can summon feelings of exhaustion. In addition to outstripping the digital output of those half her age, the 80-year-old comedian almost singlehandedly makes up for the large majority of Americans in her demographic who steer clear of all social media.

Amid jokes about celebrity fashion choices and plugs for her QVC show, Rivers reveals herself to be constantly surrounded by other celebrities, demi-celebrities, and fans — at the airport, on the red carpet, on the set of her E! show “Fashion Police,” in a green room in Phoenix, in Los Angeles, on Broadway. There she is at a wineglass-crowded dinner table with her “new BFF” Lady Gaga or delivering a cake to Orlando Bloom. Even candid shots of Rivers and her dogs reveal her peripatetic existence: She is always sitting in or emerging from a limousine, en route to a taping or a benefit or a standup gig. On Friday, she traveled to New England, where she performed in Portland, Maine, before Saturday night’s two sold-out shows at the Wilbur Theatre.

“I love the Internet, and I love that you can say whatever you want,” Rivers says in a telephone interview this week from the backseat of a car whizzing through the streets of New York City. She also loves the new fans it brings her. “My audiences get younger all the time,” she says. “But they’re [still] very gay — thank God!”

Rivers appreciates constant communication with her fans and colleagues. “Because I’m on the Internet so much, I can answer any question and keep up with these young, smart, talented comics,” she says. Among among her favorites: fellow provocateur Sarah Silverman, whom she chose as the first guest on her web series, “In Bed With Joan Rivers,” which made its debut earlier this year.

But total Internet domination, while impressive, is merely Rivers’s latest gambit in her lifelong quest to maintain relevance. Her Herculean efforts to stay funny, famous, and frantically busy are well-documented in the 2010 documentary “Joan Rivers: A Piece of Work.” In a glowing review, the late film critic Roger Ebert praised the movie’s subject as “a woman who will not accept defeat, who will not slow down, who must prove herself over and again.”

Although her medium, material and facial structure have changed throughout the years, one constant that remains is Rivers’s organization method: Her jokes are typewritten and filed by subject within something resembling a library card catalog. Although she has embraced the digital in all other areas of her life, she refuses to change her filing system.

“It’s a great reference,” she says. “I don’t want to hear about putting it on a computer, because if a computer breaks down, you’re screwed. I cannot read [digitally]. I think I was the third person in the world to get a Kindle, and I hated it from the minute I got it.”

Her joke file, she says, is a “social history of the United States. I’ll be looking through it and I’ll suddenly find a joke about Jimmy Carter, or Billy Carter! So I don’t throw any jokes away even when they’re no longer relevant.”

Besides, some topics are evergreen. “Fat jokes aren’t relevant, but they’re hilarious when you find them. We talk about Adele now, and Adele is heavy, so I might look at the Elizabeth Taylor fat jokes,” she explains.

Another ritual: opening the paper every morning to find new material. A recent favorite involves Kanye West’s new wife and her family. Rivers claims she’s not talking to her daughter, Melissa, “because she won’t do a porn tape, and I’m very angry because the Kardashians made an empire out of this,” she says. “That’s something that’s very current.”

But even someone who can joke about whether her daughter should make a sex tape has her limits: Rivers found Miley Cyrus’s performance at this year’s VMAs shocking. “When you’re the idol of young teen girls, you must respect your audience, and you shouldn’t do things that they can’t do,” she says. But fans of “Fashion Police” will know Rivers paid homage to Cyrus on Halloween when she dressed in a nude bodysuit and oversized prosthetic tongue.

“I don’t know what’s dirty anymore,” Rivers says. “Look at Sarah [Silverman’s] act, or Louis C.K.’s act, or Robin Williams’s act. Who knows what can be considered dirty when there are no boundaries? Lindsay Lohan is on drugs and comes out with a movie and everyone loves her again. When I started out, you couldn’t even say you were pregnant onstage, and now it’s all about vaginas.”

But crumbling boundaries have their own advantage: “I can say anything now,” Rivers says. “I’m totally uncensored.”