Load tsconfig.json and add extra syntastic args if found

typescript.vim

function! LoadTsConfig()
  let search_depth = 20
  let dirname = fnamemodify(expand('%'), ":p:h")
  while search_depth > 0 && dirname != "/"
    let search_depth = search_depth - 1
    let filename = dirname . "/tsconfig.json"
    " while filename
    if filereadable(filename)
      let b:tsconfig_path = filename
      let tsconfig = jsondecode(join(readfile(filename)))

      if has_key(tsconfig, "compilerOptions")
        let extra_args = ""
        for [key, val] in items(tsconfig.compilerOptions)
          if match(key, "^out") >= 0
            continue
          endif
          let extra_args = extra_args . " --" . key
          let val = tsconfig.compilerOptions[key]
          if type(val) != 6  " booleans are represented simply by being present
            let extra_args = extra_args . " " . val
          end
        endfor
        let b:syntastic_typescript_tsc_args = extra_args
      endif

      break
    endif
    let dirname = fnamemodify(dirname . "/..", ":p:h")
  endwhile
endfunction

au BufEnter *.ts call LoadTsConfig()