`deno fmt`, code formatting

Deno ships with a built-in code formatter that will auto-format the following files:

File Type	Extension	Notes
JavaScript	`.js`
TypeScript	`.ts`
JSX	`.jsx`
TSX	`.tsx`
Markdown	`.md`, `.markdown`
JSON	`.json`
JSONC	`.jsonc`
CSS	`.css`
HTML	`.html`
YAML	`.yml`, `.yaml`
Sass	`.sass`
SCSS	`.scss`
LESS	`.less`
Astro	`.astro`	Requires `--unstable-component` flag or `"unstable": ["fmt-component]` config option.
Svelte	`.svelte`	Requires `--unstable-component` flag or `"unstable": ["fmt-component]` config option.
Vue	`.vue`	Requires `--unstable-component` flag or `"unstable": ["fmt-component]` config option.

Note

deno fmt can format code snippets in Markdown files. Snippets must be enclosed in triple backticks and have a language attribute.

Examples Jump to heading

Format all supported files in the current directory and subdirectories

deno fmt

Format specific files

deno fmt myfile1.ts myfile2.ts

deno fmt index.html styles.css

Format all supported files in specified directory and subdirectories

deno fmt src/

Check if all the supported files in the current directory and subdirectories are formatted

deno fmt --check

Format stdin and write to stdout

cat file.ts | deno fmt -

Ignore formatting code by preceding it with a // deno-fmt-ignore comment:

// deno-fmt-ignore
export const identity = [
    1, 0, 0,
    0, 1, 0,
    0, 0, 1,
];

Or ignore an entire file by adding a // deno-fmt-ignore-file comment at the top of the file.

Ignore formatting next item by preceding it with  comment:

<html>
  <body>
    <p>Hello there
      <!-- deno-fmt-ignore -->
      </p>
  </body>
</html>

To ignore a section of code, surround the code with  and  comments.

Or ignore an entire file by adding a  comment at the top of the file.

Ignore formatting next item by preceding it with # deno-fmt-ignore comment:

# deno-fmt-ignore
aaaaaa:
          bbbbbbb

ℹ️ It is recommended to stick with default options.

Starting with Deno v1.14 a formatter can be customized using either a configuration file or following CLI flags:

--use-tabs - Whether to use tabs. Defaults to false (using spaces).
--line-width - The width of a line the printer will try to stay under. Note that the printer may exceed this width in certain cases. Defaults to 80.
--indent-width - The number of characters for an indent. Defaults to 2.
--no-semicolons - To not use semicolons except where necessary.
--single-quote - Whether to use single quote. Defaults to false (using double quote).
--prose-wrap={always,never,preserve} - Define how prose should be wrapped in Markdown files. Defaults to "always".

Note: In Deno versions < 1.31 you will have to prefix these flags with options- (ex. --options-use-tabs)