feat: add markdown support to deno fmt (#8887)

This commit adds support for formatting markdown files with "deno fmt".

Additionally "--ext={js|jsx|ts|tsx|md}" flag was added to "deno fmt"
that allows to specify file type when providing contents over stdio.

.dprintrc.json

@@ -22,6 +22,7 @@
     "cli/dts/typescript.d.ts",
     "cli/tests/encoding",
     "cli/tests/inline_js_source_map*",
+    "cli/tests/badly_formatted.md",
     "cli/tsc/*typescript.js",
     "test_util/wpt",
     "gh-pages",

Cargo.lock

@@ -78,7 +78,7 @@ dependencies = [
  "proc-macro2 1.0.24",
  "quote 1.0.7",
  "swc_macros_common",
- "syn 1.0.56",
+ "syn 1.0.58",
 ]
 
 [[package]]
@@ -113,7 +113,7 @@ checksum = "a3548b8efc9f8e8a5a0a2808c5bd8451a9031b9e5b879a79590304ae928b0a70"
 dependencies = [
  "proc-macro2 1.0.24",
  "quote 1.0.7",
- "syn 1.0.56",
+ "syn 1.0.58",
 ]
 
 [[package]]
@@ -124,7 +124,7 @@ checksum = "8d3a45e77e34375a7923b1e8febb049bb011f064714a8e17a1a616fef01da13d"
 dependencies = [
  "proc-macro2 1.0.24",
  "quote 1.0.7",
- "syn 1.0.56",
+ "syn 1.0.58",
 ]
 
 [[package]]
@@ -147,7 +147,7 @@ dependencies = [
  "proc-macro-error",
  "proc-macro2 1.0.24",
  "quote 1.0.7",
- "syn 1.0.56",
+ "syn 1.0.58",
 ]
 
 [[package]]
@@ -373,7 +373,7 @@ dependencies = [
  "proc-macro2 1.0.24",
  "quote 1.0.7",
  "strsim 0.9.3",
- "syn 1.0.56",
+ "syn 1.0.58",
 ]
 
 [[package]]
@@ -384,7 +384,7 @@ checksum = "d9b5a2f4ac4969822c62224815d069952656cadc7084fdca9751e6d959189b72"
 dependencies = [
  "darling_core",
  "quote 1.0.7",
- "syn 1.0.56",
+ "syn 1.0.58",
 ]
 
 [[package]]
@@ -420,6 +420,7 @@ dependencies = [
  "deno_web",
  "deno_websocket",
  "dissimilar",
+ "dprint-plugin-markdown",
  "dprint-plugin-typescript",
  "encoding_rs",
  "env_logger",
@@ -613,7 +614,7 @@ checksum = "41cb0e6161ad61ed084a36ba71fbba9e3ac5aee3606fb607fe08da6acbcf3d8c"
 dependencies = [
  "proc-macro2 1.0.24",
  "quote 1.0.7",
- "syn 1.0.56",
+ "syn 1.0.58",
 ]
 
 [[package]]
@@ -656,9 +657,9 @@ dependencies = [
 
 [[package]]
 name = "dprint-core"
-version = "0.34.0"
+version = "0.35.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c7fc292281fc3ec69dfbd36c3c5c73886469a6630e1747ff452b46f5deed208d"
+checksum = "87368d637be4fedbddd60e41958e227af4d7d32127b9a5a6cb05b0053b525f94"
 dependencies = [
  "bumpalo",
  "fnv",
@@ -666,10 +667,22 @@ dependencies = [
 ]
 
 [[package]]
-name = "dprint-plugin-typescript"
+name = "dprint-plugin-markdown"
-version = "0.38.1"
+version = "0.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "67bb41b131e30df80105eb6b4f183a4bf003ee7dfb20661ac15a2a6f329de5b1"
+checksum = "45dd3b8784047301e25e27ab168c79d86f883f65b83d26df31785cf4db144137"
+dependencies = [
+ "dprint-core",
+ "pulldown-cmark",
+ "regex",
+ "serde",
+]
+
+[[package]]
+name = "dprint-plugin-typescript"
+version = "0.38.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "54feef4e4c831395dd5874500be4b37ce9ae175c1fe1a00e3ec97abd9287a6eb"
 dependencies = [
  "dprint-core",
  "dprint-swc-ecma-ast-view",
@@ -723,7 +736,7 @@ dependencies = [
  "heck",
  "proc-macro2 1.0.24",
  "quote 1.0.7",
- "syn 1.0.56",
+ "syn 1.0.58",
 ]
 
 [[package]]
@@ -735,7 +748,7 @@ dependencies = [
  "pmutil",
  "proc-macro2 1.0.24",
  "swc_macros_common",
- "syn 1.0.56",
+ "syn 1.0.58",
 ]
 
 [[package]]
@@ -848,7 +861,7 @@ dependencies = [
  "pmutil",
  "proc-macro2 1.0.24",
  "swc_macros_common",
- "syn 1.0.56",
+ "syn 1.0.58",
 ]
 
 [[package]]
@@ -969,7 +982,7 @@ dependencies = [
  "proc-macro-hack",
  "proc-macro2 1.0.24",
  "quote 1.0.7",
- "syn 1.0.56",
+ "syn 1.0.58",
 ]
 
 [[package]]
@@ -1305,7 +1318,7 @@ dependencies = [
  "pmutil",
  "proc-macro2 1.0.24",
  "quote 1.0.7",
- "syn 1.0.56",
+ "syn 1.0.58",
 ]
 
 [[package]]
@@ -1436,7 +1449,7 @@ dependencies = [
  "heck",
  "proc-macro2 1.0.24",
  "quote 1.0.7",
- "syn 1.0.56",
+ "syn 1.0.58",
 ]
 
 [[package]]
@@ -1778,7 +1791,7 @@ dependencies = [
  "proc-macro-hack",
  "proc-macro2 1.0.24",
  "quote 1.0.7",
- "syn 1.0.56",
+ "syn 1.0.58",
 ]
 
 [[package]]
@@ -1816,7 +1829,7 @@ checksum = "2c0e815c3ee9a031fdf5af21c10aa17c573c9c6a566328d99e3936c34e36461f"
 dependencies = [
  "proc-macro2 1.0.24",
  "quote 1.0.7",
- "syn 1.0.56",
+ "syn 1.0.58",
 ]
 
 [[package]]
@@ -1827,7 +1840,7 @@ checksum = "caa25a6393f22ce819b0f50e0be89287292fda8d425be38ee0ca14c4931d9e71"
 dependencies = [
  "proc-macro2 1.0.24",
  "quote 1.0.7",
- "syn 1.0.56",
+ "syn 1.0.58",
 ]
 
 [[package]]
@@ -1850,7 +1863,7 @@ checksum = "3894e5d549cccbe44afecf72922f277f603cd4bb0219c8342631ef18fffbe004"
 dependencies = [
  "proc-macro2 1.0.24",
  "quote 1.0.7",
- "syn 1.0.56",
+ "syn 1.0.58",
 ]
 
 [[package]]
@@ -1874,7 +1887,7 @@ dependencies = [
  "proc-macro-error-attr",
  "proc-macro2 1.0.24",
  "quote 1.0.7",
- "syn 1.0.56",
+ "syn 1.0.58",
  "version_check",
 ]
 
@@ -1929,6 +1942,17 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "pulldown-cmark"
+version = "0.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ffade02495f22453cd593159ea2f59827aae7f53fa8323f756799b670881dcf8"
+dependencies = [
+ "bitflags",
+ "memchr",
+ "unicase",
+]
+
 [[package]]
 name = "quick-error"
 version = "1.2.3"
@@ -2236,7 +2260,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "db9dfbf470021de34cfaf6983067f460ea19164934a7c2d4b92eec0968eb95f1"
 dependencies = [
  "quote 1.0.7",
- "syn 1.0.56",
+ "syn 1.0.58",
 ]
 
 [[package]]
@@ -2317,7 +2341,7 @@ checksum = "c84d3526699cd55261af4b941e4e725444df67aa4f9e6a3564f18030d12672df"
 dependencies = [
  "proc-macro2 1.0.24",
  "quote 1.0.7",
- "syn 1.0.56",
+ "syn 1.0.58",
 ]
 
 [[package]]
@@ -2340,7 +2364,7 @@ checksum = "2dc6b7951b17b051f3210b063f12cc17320e2fe30ae05b0fe2a3abb068551c76"
 dependencies = [
  "proc-macro2 1.0.24",
  "quote 1.0.7",
- "syn 1.0.56",
+ "syn 1.0.58",
 ]
 
 [[package]]
@@ -2477,7 +2501,7 @@ dependencies = [
  "proc-macro2 1.0.24",
  "quote 1.0.7",
  "swc_macros_common",
- "syn 1.0.56",
+ "syn 1.0.58",
 ]
 
 [[package]]
@@ -2593,7 +2617,7 @@ dependencies = [
  "proc-macro2 1.0.24",
  "quote 1.0.7",
  "swc_macros_common",
- "syn 1.0.56",
+ "syn 1.0.58",
 ]
 
 [[package]]
@@ -2796,7 +2820,7 @@ dependencies = [
  "pmutil",
  "proc-macro2 1.0.24",
  "quote 1.0.7",
- "syn 1.0.56",
+ "syn 1.0.58",
 ]
 
 [[package]]
@@ -2808,7 +2832,7 @@ dependencies = [
  "pmutil",
  "proc-macro2 1.0.24",
  "quote 1.0.7",
- "syn 1.0.56",
+ "syn 1.0.58",
 ]
 
 [[package]]
@@ -2832,7 +2856,7 @@ dependencies = [
  "proc-macro2 1.0.24",
  "quote 1.0.7",
  "swc_macros_common",
- "syn 1.0.56",
+ "syn 1.0.58",
 ]
 
 [[package]]
@@ -2848,9 +2872,9 @@ dependencies = [
 
 [[package]]
 name = "syn"
-version = "1.0.56"
+version = "1.0.58"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a9802ddde94170d186eeee5005b798d9c159fa970403f1be19976d0cfb939b72"
+checksum = "cc60a3d73ea6594cd712d830cc1f0390fd71542d8c8cd24e70cc54cdfd5e05d5"
 dependencies = [
  "proc-macro2 1.0.24",
  "quote 1.0.7",
@@ -2950,7 +2974,7 @@ checksum = "bd80fc12f73063ac132ac92aceea36734f04a1d93c1240c6944e23a3b8841793"
 dependencies = [
  "proc-macro2 1.0.24",
  "quote 1.0.7",
- "syn 1.0.56",
+ "syn 1.0.58",
 ]
 
 [[package]]
@@ -3007,7 +3031,7 @@ checksum = "42517d2975ca3114b22a16192634e8241dc5cc1f130be194645970cc1c371494"
 dependencies = [
  "proc-macro2 1.0.24",
  "quote 1.0.7",
- "syn 1.0.56",
+ "syn 1.0.58",
 ]
 
 [[package]]
@@ -3263,6 +3287,15 @@ version = "0.1.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "56dee185309b50d1f11bfedef0fe6d036842e3fb77413abef29f8f8d1c5d4c1c"
 
+[[package]]
+name = "unicase"
+version = "2.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "50f37be617794602aabbeee0be4f259dc1778fabe05e2d67ee8f79326d5cb4f6"
+dependencies = [
+ "version_check",
+]
+
 [[package]]
 name = "unicode-bidi"
 version = "0.3.4"
@@ -3413,7 +3446,7 @@ dependencies = [
  "log",
  "proc-macro2 1.0.24",
  "quote 1.0.7",
- "syn 1.0.56",
+ "syn 1.0.58",
  "wasm-bindgen-shared",
 ]
 
@@ -3447,7 +3480,7 @@ checksum = "f249f06ef7ee334cc3b8ff031bfc11ec99d00f34d86da7498396dc1e3b1498fe"
 dependencies = [
  "proc-macro2 1.0.24",
  "quote 1.0.7",
- "syn 1.0.56",
+ "syn 1.0.58",
  "wasm-bindgen-backend",
  "wasm-bindgen-shared",
 ]

cli/Cargo.toml

@@ -46,7 +46,8 @@ base64 = "0.13.0"
 byteorder = "1.4.2"
 clap = "2.33.3"
 dissimilar = "1.0.2"
-dprint-plugin-typescript = "0.38.1"
+dprint-plugin-typescript = "0.38.3"
+dprint-plugin-markdown = "0.5.1"
 encoding_rs = "0.8.26"
 env_logger = "0.8.2"
 filetime = "0.2.13"

cli/flags.rs

@@ -50,6 +50,7 @@ pub enum DenoSubcommand {
     check: bool,
     files: Vec<PathBuf>,
     ignore: Vec<PathBuf>,
+    ext: String,
   },
   Info {
     json: bool,
@@ -400,8 +401,11 @@ fn fmt_parse(flags: &mut Flags, matches: &clap::ArgMatches) {
     Some(f) => f.map(PathBuf::from).collect(),
     None => vec![],
   };
+  let ext = matches.value_of("ext").unwrap().to_string();
+
   flags.subcommand = DenoSubcommand::Fmt {
     check: matches.is_present("check"),
+    ext,
     files,
     ignore,
   }
@@ -809,6 +813,14 @@ Ignore formatting a file by adding an ignore comment at the top of the file:
         .help("Check if the source files are formatted")
         .takes_value(false),
     )
+    .arg(
+      Arg::with_name("ext")
+        .long("ext")
+        .help("Set standard input (stdin) content type")
+        .takes_value(true)
+        .default_value("ts")
+        .possible_values(&["ts", "tsx", "js", "jsx", "md"]),
+    )
     .arg(
       Arg::with_name("ignore")
         .long("ignore")
@@ -1991,6 +2003,7 @@ mod tests {
             PathBuf::from("script_1.ts"),
             PathBuf::from("script_2.ts")
           ],
+          ext: "ts".to_string()
         },
         ..Flags::default()
       }
@@ -2004,6 +2017,7 @@ mod tests {
           ignore: vec![],
           check: true,
           files: vec![],
+          ext: "ts".to_string(),
         },
         ..Flags::default()
       }
@@ -2017,6 +2031,7 @@ mod tests {
           ignore: vec![],
           check: false,
           files: vec![],
+          ext: "ts".to_string(),
         },
         ..Flags::default()
       }
@@ -2030,6 +2045,7 @@ mod tests {
           ignore: vec![],
           check: false,
           files: vec![],
+          ext: "ts".to_string(),
         },
         watch: true,
         unstable: true,
@@ -2053,6 +2069,7 @@ mod tests {
           ignore: vec![PathBuf::from("bar.js")],
           check: true,
           files: vec![PathBuf::from("foo.ts")],
+          ext: "ts".to_string(),
         },
         watch: true,
         unstable: true,

cli/fs_util.rs

@@ -90,17 +90,30 @@ pub fn resolve_from_cwd(path: &Path) -> Result<PathBuf, AnyError> {
 
 /// Checks if the path has extension Deno supports.
 pub fn is_supported_ext(path: &Path) -> bool {
-  let lowercase_ext = path
+  if let Some(ext) = get_extension(path) {
-    .extension()
+    matches!(ext.as_str(), "ts" | "tsx" | "js" | "jsx" | "mjs")
-    .and_then(|e| e.to_str())
-    .map(|e| e.to_lowercase());
-  if let Some(ext) = lowercase_ext {
-    ext == "ts" || ext == "tsx" || ext == "js" || ext == "jsx" || ext == "mjs"
   } else {
     false
   }
 }
 
+/// This function is similar to is_supported_ext but also allows .md extension.
+pub fn is_supported_ext_md(path: &Path) -> bool {
+  if let Some(ext) = get_extension(path) {
+    matches!(ext.as_str(), "ts" | "tsx" | "js" | "jsx" | "mjs" | "md")
+  } else {
+    false
+  }
+}
+
+/// Get the extension of a file in lowercase.
+pub fn get_extension(file_path: &Path) -> Option<String> {
+  return file_path
+    .extension()
+    .and_then(|e| e.to_str())
+    .map(|e| e.to_lowercase());
+}
+
 /// Collects file paths that satisfy the given predicate, by recursively walking `files`.
 /// If the walker visits a path that is listed in `ignore`, it skips descending into the directory.
 pub fn collect_files<P>(
@@ -207,6 +220,24 @@ mod tests {
     assert!(!is_supported_ext(Path::new("foo.mjsx")));
   }
 
+  #[test]
+  fn test_is_supported_ext_md() {
+    assert!(!is_supported_ext_md(Path::new("tests/subdir/redirects")));
+    assert!(is_supported_ext_md(Path::new("README.md")));
+    assert!(is_supported_ext_md(Path::new("readme.MD")));
+    assert!(is_supported_ext_md(Path::new("lib/typescript.d.ts")));
+    assert!(is_supported_ext_md(Path::new("cli/tests/001_hello.js")));
+    assert!(is_supported_ext_md(Path::new("cli/tests/002_hello.ts")));
+    assert!(is_supported_ext_md(Path::new("foo.jsx")));
+    assert!(is_supported_ext_md(Path::new("foo.tsx")));
+    assert!(is_supported_ext_md(Path::new("foo.TS")));
+    assert!(is_supported_ext_md(Path::new("foo.TSX")));
+    assert!(is_supported_ext_md(Path::new("foo.JS")));
+    assert!(is_supported_ext_md(Path::new("foo.JSX")));
+    assert!(is_supported_ext_md(Path::new("foo.mjs")));
+    assert!(!is_supported_ext_md(Path::new("foo.mjsx")));
+  }
+
   #[test]
   fn test_collect_files() {
     fn create_files(dir_path: &PathBuf, files: &[&str]) {

cli/main.rs

@@ -807,9 +807,10 @@ async fn format_command(
   args: Vec<PathBuf>,
   ignore: Vec<PathBuf>,
   check: bool,
+  ext: String,
 ) -> Result<(), AnyError> {
   if args.len() == 1 && args[0].to_string_lossy() == "-" {
-    return tools::fmt::format_stdin(check);
+    return tools::fmt::format_stdin(check, ext);
   }
 
   tools::fmt::format(args, ignore, check, flags.watch).await?;
@@ -1179,7 +1180,8 @@ fn get_subcommand(
       check,
       files,
       ignore,
-    } => format_command(flags, files, ignore, check).boxed_local(),
+      ext,
+    } => format_command(flags, files, ignore, check, ext).boxed_local(),
     DenoSubcommand::Info { file, json } => {
       info_command(flags, file, json).boxed_local()
     }

cli/tests/badly_formatted.md

@@ -0,0 +1,28 @@
+# Hello      Markdown
+
+```js
+console.log("Hello World"
+
+)
+```
+
+```javascript
+console.log("Hello World2"
+
+)
+```
+
+```ts
+
+function hello(name: string    ) {
+                  console.log(name);
+};
+
+hello(        "alice");
+```
+
+```typescript
+function foo(): number {
+  return       2;
+}
+```

cli/tests/badly_formatted_fixed.md

@@ -0,0 +1,23 @@
+# Hello Markdown
+
+```js
+console.log("Hello World");
+```
+
+```javascript
+console.log("Hello World2");
+```
+
+```ts
+function hello(name: string) {
+  console.log(name);
+}
+
+hello("alice");
+```
+
+```typescript
+function foo(): number {
+  return 2;
+}
+```

cli/tests/fmt/expected_fmt_check_formatted_files.out

@@ -1 +1 @@
-Checked 2 files
+Checked 3 files

cli/tests/fmt/expected_fmt_check_ignore.out

@@ -1 +1 @@
-Checked 1 file
+Checked 2 files

cli/tests/fmt/expected_fmt_check_tests_dir.out

@@ -1,2 +1,2 @@
 [WILDCARD]
-error: Found 5 not formatted files in [WILDCARD] files
+error: Found 6 not formatted files in [WILDCARD] files

cli/tests/fmt/formatted3.md

@@ -0,0 +1,17 @@
+# Hello
+
+```js
+function foo() {
+  return 42;
+}
+
+foo();
+```
+
+```ts
+function bar(): number {
+  return 42;
+}
+
+bar();
+```

cli/tests/integration_tests.rs

@@ -511,20 +511,31 @@ fn cache_invalidation_test_no_check() {
 #[test]
 fn fmt_test() {
   let t = TempDir::new().expect("tempdir fail");
-  let fixed = util::root_path().join("cli/tests/badly_formatted_fixed.js");
+  let fixed_js = util::root_path().join("cli/tests/badly_formatted_fixed.js");
-  let badly_formatted_original =
+  let fixed_md = util::root_path().join("cli/tests/badly_formatted_fixed.md");
+  let badly_formatted_original_js =
     util::root_path().join("cli/tests/badly_formatted.mjs");
-  let badly_formatted = t.path().join("badly_formatted.js");
+  let badly_formatted_original_md =
-  let badly_formatted_str = badly_formatted.to_str().unwrap();
+    util::root_path().join("cli/tests/badly_formatted.md");
-  std::fs::copy(&badly_formatted_original, &badly_formatted)
+  let badly_formatted_js = t.path().join("badly_formatted.js");
+  let badly_formatted_md = t.path().join("badly_formatted.md");
+  let badly_formatted_js_str = badly_formatted_js.to_str().unwrap();
+  let badly_formatted_md_str = badly_formatted_md.to_str().unwrap();
+  std::fs::copy(&badly_formatted_original_js, &badly_formatted_js)
+    .expect("Failed to copy file");
+  std::fs::copy(&badly_formatted_original_md, &badly_formatted_md)
     .expect("Failed to copy file");
   // First, check formatting by ignoring the badly formatted file.
   let status = util::deno_cmd()
     .current_dir(util::root_path())
     .arg("fmt")
-    .arg(format!("--ignore={}", badly_formatted_str))
+    .arg(format!(
+      "--ignore={},{}",
+      badly_formatted_js_str, badly_formatted_md_str
+    ))
     .arg("--check")
-    .arg(badly_formatted_str)
+    .arg(badly_formatted_js_str)
+    .arg(badly_formatted_md_str)
     .spawn()
     .expect("Failed to spawn script")
     .wait()
@@ -535,7 +546,8 @@ fn fmt_test() {
     .current_dir(util::root_path())
     .arg("fmt")
     .arg("--check")
-    .arg(badly_formatted_str)
+    .arg(badly_formatted_js_str)
+    .arg(badly_formatted_md_str)
     .spawn()
     .expect("Failed to spawn script")
     .wait()
@@ -545,15 +557,19 @@ fn fmt_test() {
   let status = util::deno_cmd()
     .current_dir(util::root_path())
     .arg("fmt")
-    .arg(badly_formatted_str)
+    .arg(badly_formatted_js_str)
+    .arg(badly_formatted_md_str)
     .spawn()
     .expect("Failed to spawn script")
     .wait()
     .expect("Failed to wait for child process");
   assert!(status.success());
-  let expected = std::fs::read_to_string(fixed).unwrap();
+  let expected_js = std::fs::read_to_string(fixed_js).unwrap();
-  let actual = std::fs::read_to_string(badly_formatted).unwrap();
+  let expected_md = std::fs::read_to_string(fixed_md).unwrap();
-  assert_eq!(expected, actual);
+  let actual_js = std::fs::read_to_string(badly_formatted_js).unwrap();
+  let actual_md = std::fs::read_to_string(badly_formatted_md).unwrap();
+  assert_eq!(expected_js, actual_js);
+  assert_eq!(expected_md, actual_md);
 }
 
 // Helper function to skip watcher output that contains "Restarting"
@@ -2751,7 +2767,7 @@ itest!(fmt_quiet_check_fmt_dir {
 });
 
 itest!(fmt_check_formatted_files {
-  args: "fmt --check fmt/formatted1.js fmt/formatted2.ts",
+  args: "fmt --check fmt/formatted1.js fmt/formatted2.ts fmt/formatted3.md",
   output: "fmt/expected_fmt_check_formatted_files.out",
   exit_code: 0,
 });
@@ -2768,6 +2784,12 @@ itest!(fmt_stdin {
   output_str: Some("const a = 1;\n"),
 });
 
+itest!(fmt_stdin_markdown {
+  args: "fmt --ext=md -",
+  input: Some("# Hello      Markdown\n```ts\nconsole.log( \"text\")\n```\n"),
+  output_str: Some("# Hello Markdown\n\n```ts\nconsole.log(\"text\");\n```\n"),
+});
+
 itest!(fmt_stdin_check_formatted {
   args: "fmt --check -",
   input: Some("const a = 1;\n"),

cli/tools/fmt.rs

@@ -10,13 +10,12 @@
 use crate::colors;
 use crate::diff::diff;
 use crate::file_watcher;
-use crate::fs_util::{collect_files, is_supported_ext};
+use crate::fs_util::{collect_files, get_extension, is_supported_ext_md};
 use crate::text_encoding;
 use deno_core::error::generic_error;
 use deno_core::error::AnyError;
 use deno_core::futures;
 use deno_core::futures::FutureExt;
-use dprint_plugin_typescript as dprint;
 use std::fs;
 use std::io::stdin;
 use std::io::stdout;
@@ -38,11 +37,10 @@ pub async fn format(
 ) -> Result<(), AnyError> {
   let target_file_resolver = || {
     // collect the files that are to be formatted
-    collect_files(&args, &ignore, is_supported_ext)
+    collect_files(&args, &ignore, is_supported_ext_md)
   };
-
   let operation = |paths: Vec<PathBuf>| {
-    let config = get_config();
+    let config = get_typescript_config();
     async move {
       if check {
         check_source_files(config, paths).await?;
@@ -63,8 +61,48 @@ pub async fn format(
   Ok(())
 }
 
+/// Formats markdown (using https://github.com/dprint/dprint-plugin-markdown) and its code blocks
+/// (ts/tsx, js/jsx).
+fn format_markdown(
+  file_text: &str,
+  ts_config: dprint_plugin_typescript::configuration::Configuration,
+) -> Result<String, String> {
+  let md_config = get_markdown_config();
+  dprint_plugin_markdown::format_text(
+    &file_text,
+    &md_config,
+    Box::new(move |tag, text, line_width| {
+      let tag = tag.to_lowercase();
+      if matches!(
+        tag.as_str(),
+        "ts" | "tsx" | "js" | "jsx" | "javascript" | "typescript"
+      ) {
+        // It's important to tell dprint proper file extension, otherwise
+        // it might parse the file twice.
+        let extension = match tag.as_str() {
+          "javascript" => "js",
+          "typescript" => "ts",
+          rest => rest,
+        };
+        let fake_filename =
+          PathBuf::from(format!("deno_fmt_stdin.{}", extension));
+
+        let mut codeblock_config = ts_config.clone();
+        codeblock_config.line_width = line_width;
+        dprint_plugin_typescript::format_text(
+          &fake_filename,
+          &text,
+          &codeblock_config,
+        )
+      } else {
+        Ok(text.to_string())
+      }
+    }),
+  )
+}
+
 async fn check_source_files(
-  config: dprint::configuration::Configuration,
+  config: dprint_plugin_typescript::configuration::Configuration,
   paths: Vec<PathBuf>,
 ) -> Result<(), AnyError> {
   let not_formatted_files_count = Arc::new(AtomicUsize::new(0));
@@ -79,7 +117,12 @@ async fn check_source_files(
     move |file_path| {
       checked_files_count.fetch_add(1, Ordering::Relaxed);
       let file_text = read_file_contents(&file_path)?.text;
-      let r = dprint::format_text(&file_path, &file_text, &config);
+      let ext = get_extension(&file_path).unwrap_or_else(String::new);
+      let r = if ext == "md" {
+        format_markdown(&file_text, config.clone())
+      } else {
+        dprint_plugin_typescript::format_text(&file_path, &file_text, &config)
+      };
       match r {
         Ok(formatted_text) => {
           if formatted_text != file_text {
@@ -120,7 +163,7 @@ async fn check_source_files(
 }
 
 async fn format_source_files(
-  config: dprint::configuration::Configuration,
+  config: dprint_plugin_typescript::configuration::Configuration,
   paths: Vec<PathBuf>,
 ) -> Result<(), AnyError> {
   let formatted_files_count = Arc::new(AtomicUsize::new(0));
@@ -133,7 +176,16 @@ async fn format_source_files(
     move |file_path| {
       checked_files_count.fetch_add(1, Ordering::Relaxed);
       let file_contents = read_file_contents(&file_path)?;
-      let r = dprint::format_text(&file_path, &file_contents.text, &config);
+      let ext = get_extension(&file_path).unwrap_or_else(String::new);
+      let r = if ext == "md" {
+        format_markdown(&file_contents.text, config.clone())
+      } else {
+        dprint_plugin_typescript::format_text(
+          &file_path,
+          &file_contents.text,
+          &config,
+        )
+      };
       match r {
         Ok(formatted_text) => {
           if formatted_text != file_contents.text {
@@ -178,17 +230,25 @@ async fn format_source_files(
 }
 
 /// Format stdin and write result to stdout.
-/// Treats input as TypeScript.
+/// Treats input as TypeScript or as set by `--ext` flag.
 /// Compatible with `--check` flag.
-pub fn format_stdin(check: bool) -> Result<(), AnyError> {
+pub fn format_stdin(check: bool, ext: String) -> Result<(), AnyError> {
   let mut source = String::new();
   if stdin().read_to_string(&mut source).is_err() {
     return Err(generic_error("Failed to read from stdin"));
   }
-  let config = get_config();
+  let config = get_typescript_config();
-
+  let r = if ext.as_str() == "md" {
-  // dprint will fallback to jsx parsing if parsing this as a .ts file doesn't work
+    format_markdown(&source, config)
-  match dprint::format_text(&PathBuf::from("_stdin.ts"), &source, &config) {
+  } else {
+    // dprint will fallback to jsx parsing if parsing this as a .ts file doesn't work
+    dprint_plugin_typescript::format_text(
+      &PathBuf::from("_stdin.ts"),
+      &source,
+      &config,
+    )
+  };
+  match r {
     Ok(formatted_text) => {
       if check {
         if formatted_text != source {
@@ -213,9 +273,22 @@ fn files_str(len: usize) -> &'static str {
   }
 }
 
-fn get_config() -> dprint::configuration::Configuration {
+fn get_typescript_config(
-  use dprint::configuration::*;
+) -> dprint_plugin_typescript::configuration::Configuration {
-  ConfigurationBuilder::new().deno().build()
+  dprint_plugin_typescript::configuration::ConfigurationBuilder::new()
+    .deno()
+    .build()
+}
+
+fn get_markdown_config() -> dprint_plugin_markdown::configuration::Configuration
+{
+  dprint_plugin_markdown::configuration::ConfigurationBuilder::new()
+    // Matches `.dprintrc.json` in the repository
+    .text_wrap(dprint_plugin_markdown::configuration::TextWrap::Always)
+    .ignore_directive("deno-fmt-ignore")
+    .ignore_start_directive("deno-fmt-ignore-start")
+    .ignore_end_directive("deno-fmt-ignore-end")
+    .build()
 }
 
 struct FileContents {