Read tsconfig dynamically

typescript_neomake.vim

let s:enabled_options = [
    \ 'target', 'emitDecoratorMetadata', 'experimentalDecorators', 'module',
    \ 'noImplicitAny', 'rootDir', 'noEmit', 'allowSyntheticDefaultImports',
    \ 'noImplicitReturn', 'allowUnreachableCode', 'allowUnusedLabels'
]

function! neomake#makers#ft#typescript#tsc()
    let l:tsconfig = findfile('tsconfig.json', '.;')
    if len(l:tsconfig)
        let true = 1
        let false = 0
        let null = 0
        " ugly shortcut
        let l:jsonText = join(readfile(l:tsconfig, 'b'), '')
        let l:json = eval(l:jsonText)
        let l:option = get(l:json, 'compilerOptions', {})
        let l:option['noEmit'] = 1
        let l:args = []
        if !len(get(l:option, 'rootDir', ''))
            let l:option['rootDir'] = fnamemodify(l:tsconfig, ':h')
        endif
        for [key, value] in items(l:option)
            if index(s:enabled_options, key) == -1
                continue
            endif
            if value == 1
                call insert(l:args, '--'.key)
            elseif type(value) == type('')
                call insert(l:args, value)
                call insert(l:args, '--'.key)
            endif
        endfor
    else
        let l:args = [
            \ '-m', 'commonjs', '--noEmit', '--rootDir', '.'
        \ ]
    endif

    return {
        \ 'args': l:args,
        \ 'errorformat':
            \ '%E%f %#(%l\,%c): error %m,' .
            \ '%E%f %#(%l\,%c): %m,' .
            \ '%Eerror %m,' .
            \ '%C%\s%\+%m'
        \ }
endfunction