Add 'prettier' fixer support to TypeScript, CSS, SCSS and JSON (#910)

* Add prettier fixer support for typescript

* Add prettier fixer support for css and scss

* Add prettier fixer support for json

* Use getbufvar() to get &filetype

autoload/ale/fix/registry.vim

@@ -34,7 +34,7 @@ let s:default_registry = {
 \   },
 \   'prettier': {
 \       'function': 'ale#fixers#prettier#Fix',
-\       'suggested_filetypes': ['javascript'],
+\       'suggested_filetypes': ['javascript', 'typescript', 'json', 'css', 'scss'],
 \       'description': 'Apply prettier to a file.',
 \   },
 \   'prettier_eslint': {

autoload/ale/fixers/prettier.vim

@@ -38,6 +38,22 @@ function! ale#fixers#prettier#Fix(buffer) abort
     let l:config = s:FindConfig(a:buffer)
     let l:use_config = ale#Var(a:buffer, 'javascript_prettier_use_local_config')
                 \ && !empty(l:config)
+    let l:filetype = getbufvar(a:buffer, '&filetype')
+
+    " Append the --parser flag depending on the current filetype (unless it's
+    " already set in g:javascript_prettier_options).
+    if match(l:options, '--parser') == -1
+        if l:filetype is# 'typescript'
+            let l:parser = 'typescript'
+        elseif l:filetype =~# 'css\|scss'
+            let l:parser = 'postcss'
+        elseif l:filetype is# 'json'
+            let l:parser = 'json'
+        else
+            let l:parser = 'babylon'
+        endif
+        let l:options = (!empty(l:options) ? l:options . ' ' : '') . '--parser ' . l:parser
+    endif
 
     return {
     \   'command': ale#Escape(ale#fixers#prettier#GetExecutable(a:buffer))