During the economy’s slow crawl back from recession, many companies have cut out lavish holiday parties. But with the Nasdaq up 11 percent for the year and companies like Uber raising record amounts of investment capital at valuations in the billions or tens of billions of dollars, the Bay Area’s tech elite is feeling celebratory. On Dec. 6 at AT&T Park, the home of the reigning champion San Francisco Giants, a jazz band welcomed thousands of Facebook employees and their guests into a large white party tent spanning the outfield, accented with giant hanging lights in the shape of baseballs. Guests danced, played beer pong on Facebook-branded tables, and took selfies in front of a 6-foot-tall baseball-filled Facebook logo. The World Series trophy and Giants mascot Lou Seal were on display and available for photos, and a live feed of the party streamed on the park’s jumbotron as revelers enjoyed ballpark hot dogs alongside macarons and fancier fare. The cost of booking the stadium is $200,000.