JS is definitely more popular, but you can run Lua inside PosgreSQL as well, and I fail to see the point of asm.js on the server. You can pick up Lua in a day

JS is definitely more popular, but you can run Lua inside PosgreSQL as well, and I fail to see the point of asm.js on the server. You can pick up Lua in a day if you can already program, by reading Roberto Ierusalimschi's Programming in Lua.