Which came first, Harry Potter or JavaScript?

JavaScript came first, by 2 years. Brendan Eich wrote it in ten days for Netscape Navigator.

Side by side

Harry Potter

Bloomsbury published the first book in June 1997 with a print run of 500 copies, most of which went to libraries, after twelve other publishers had rejected the manuscript. The company's chairman gave the first chapter to his eight-year-old daughter, who demanded the rest. It came out the same year as Netflix was founded and a year before Google.

JavaScript

JavaScript was written in about ten days in May 1995, shipped in Netscape Navigator 2.0 later that year, and was called LiveScript until December, when Netscape renamed it as part of a marketing deal with Sun. It has nothing to do with Java beyond some borrowed syntax. Standardisation as ECMAScript followed in 1997, and the language spent a decade being treated as a toy before it became the most widely deployed programming language in the world.