feat: add deno fmt (#46)

README.md

@@ -165,6 +165,7 @@ To view configured and available formatters, as well as to see the path to the l
 - [cljstyle](https://github.com/greglook/cljstyle) - Formatter for Clojure code.
 - [cmake_format](https://github.com/cheshirekow/cmake_format) - Parse cmake listfiles and format them nicely.
 - [dart_format](https://dart.dev/tools/dart-format) - Replace the whitespace in your program with formatting that follows Dart guidelines.
+- [deno_fmt](https://deno.land/manual/tools/formatter) - Use [Deno](https://deno.land/) to format TypeScript, JavaScript/JSON and markdown.
 - [dfmt](https://github.com/dlang-community/dfmt) - Formatter for D source code.
 - [djlint](https://github.com/Riverside-Healthcare/djLint) - ✨ HTML Template Linter and Formatter. Django - Jinja - Nunjucks - Handlebars - GoLang.
 - [elm_format](https://github.com/avh4/elm-format) - elm-format formats Elm source code according to a standard set of rules based on the official [Elm Style Guide](https://elm-lang.org/docs/style-guide).

doc/conform.txt

@@ -160,6 +160,8 @@ FORMATTERS                                                    *conform-formatter
 `cmake_format` - Parse cmake listfiles and format them nicely.
 `dart_format` - Replace the whitespace in your program with formatting that
               follows Dart guidelines.
+`deno_fmt` - Use [Deno](https://deno.land/) to format TypeScript,
+           JavaScript/JSON and markdown.
 `dfmt` - Formatter for D source code.
 `djlint` - ✨ HTML Template Linter and Formatter. Django - Jinja - Nunjucks -
          Handlebars - GoLang.

lua/conform/formatters/deno_fmt.lua

@@ -0,0 +1,25 @@
+local extensions = {
+  javascript = "js",
+  javascriptreact = "jsx",
+  json = "json",
+  jsonc = "jsonc",
+  markdown = "md",
+  typescript = "ts",
+  typescriptreact = "tsx",
+}
+---@type conform.FileFormatterConfig
+return {
+  meta = {
+    url = "https://deno.land/manual/tools/formatter",
+    description = "Use [Deno](https://deno.land/) to format TypeScript, JavaScript/JSON and markdown.",
+  },
+  command = "deno",
+  args = function(ctx)
+    return {
+      "fmt",
+      "-",
+      "--ext",
+      extensions[vim.bo[ctx.buf].filetype],
+    }
+  end,
+}