taxsim.js

tooling to generate a JS/WebAssembly version of NBER TAXSIM

Uses the gfortran/dragonegg toolchain from StarGate01/Full-Stack-Fortran to convert taxsim.f from fixed-mode f90 fortran into LLVM bitcode, then uses emscripten to convert LLVM bitcode into a JS/WASM wrapper.

Note: taxsim.f is not included, and must be obtained separately from the NBER.

converting taxsim.f to WASM

$ make taxsim.js

the Makefile uses docker and the stargate01/f90wasm container to compile our fortran code. see Dockerfile for the build commands.

using taxsim.js

function taxsim(input: String): Promise
function taxsim(input: Object): Promise

let input = "taxsimid,mstat,year,ltcg,idtl\n1,2,1970,100000,5"
let output = await taxsim(input)
let output = await taxsim({
  year: 2020,
  mstat: 2,
  ltcg: 100000
})

in a browser

• see demo.html (source) or the live version

via node.js

• bash:

  $ printf "year,mstat\n2020,2" | node -e "require('./taxsim.js')()"
  $ node --input-type=module -e "import taxsim from './taxsim.js'; console.log(await taxsim({year:2020,mstat:2}))"

• powershell:

  > "year,mstat`n2020,2" | node -e "require('./taxsim.js')()"

via libv8

• d8:

  $ printf "year,mstat\n2020,2\n" | d8 -e "load('./taxsim.js'); taxsim()"
  $ d8 -e "load('./taxsim.js'); function quit(){}; taxsim({year:2020,mstat:2}).then(console.log).catch(console.log)"

• V8 for R:

  > download.file("https://taxsim.app/taxsim.wasm", "taxsim.wasm", mode="wb")
  > download.file("https://taxsim.app/taxsim.js", "taxsim.js")
  
  > library(V8)
  > ctx <- v8()
  > ctx$assign("wasmBinary", readBin("taxsim.wasm", raw(), file.info("taxsim.wasm")$size))
  > ctx$source("taxsim.js")
  > ctx$call("taxsim", JS("{year:2020, mstat:2}"), JS("{wasmBinary}"), await=TRUE)

projects using taxsim.js

• https://taxsim.app (tmm1/taxsim.app)
• https://www.shaneorr.io/r/usincometaxes/ (shanejorr/usincometaxes)