On July 16, “The Catcher in the Rye,” by J.D. Salinger, will turn 75. Commemorating such a nice big number would surely strike its adolescent hero, Holden Caulfield, as the absolute nadir of “corny,” but maybe we could use a little corn, as the data centers invade our farmland. Pour out a Scotch and soda — make that a malted milk — for this spry codger of a novel that’s stayed on the dance floor long past when might be expected, leaping over book bans from the right and dodging cancellation from the left. “Catcher” has somehow inspired artists as...