prettier-plugin-svelte

What is prettier-plugin-svelte?

The prettier-plugin-svelte npm package is a plugin for Prettier that adds support for formatting Svelte files. It ensures that your Svelte code is consistently styled according to Prettier's rules, making it easier to maintain and read.

What are prettier-plugin-svelte's main functionalities?

Format Svelte Files

This feature allows you to format Svelte files using Prettier. By including the plugin in your Prettier configuration, you can ensure that your Svelte code is consistently styled.

/* .prettierrc */
{
  "plugins": ["prettier-plugin-svelte"]
}

/* Example Svelte file before formatting */
<script>
  let count = 0;
  function increment() {
    count += 1;
  }
</script>

<style>
  h1 {
    color: red;
  }
</style>

<h1 on:click={increment}>Count: {count}</h1>

/* Example Svelte file after formatting */
<script>
  let count = 0;
  function increment() {
    count += 1;
  }
</script>

<style>
  h1 {
    color: red;
  }
</style>

<h1 on:click={increment}>Count: {count}</h1>

Integration with Prettier CLI

You can use the Prettier CLI to format all Svelte files in your project. This command will recursively find and format all .svelte files in the src directory.

/* Command to format Svelte files using Prettier CLI */
npx prettier --write "src/**/*.svelte"

Support for Svelte-specific Syntax

The plugin supports Svelte-specific syntax such as reactive statements, bindings, and event handlers, ensuring that these are also formatted correctly.

/* Example Svelte file with Svelte-specific syntax */
<script>
  export let name = 'world';
</script>

<style>
  p {
    font-size: 1.5em;
  }
</style>

<p>Hello {name}!</p>

Other packages similar to prettier-plugin-svelte

eslint-plugin-svelte3

eslint-plugin-svelte3 is an ESLint plugin that provides linting for Svelte files. While it focuses on linting rather than formatting, it can be used alongside prettier-plugin-svelte to ensure both code quality and consistent styling.

svelte-preprocess

svelte-preprocess is a preprocessor for Svelte that allows you to use various languages like TypeScript, SCSS, and PostCSS in your Svelte components. While it doesn't handle formatting, it can be used in conjunction with prettier-plugin-svelte to preprocess and format your Svelte code.

svelte-check

svelte-check is a command-line tool that provides type-checking and linting for Svelte projects. It complements prettier-plugin-svelte by ensuring that your Svelte code is not only well-formatted but also free of type errors and common issues.

README

Prettier for Svelte 3 components

Format your Svelte components using Prettier.

Features

• Format your HTML, CSS, and JavaScript using prettier
• Format Svelte syntax, e.g. each loops, if statements, await blocks, etc.
• Format the JavaScript expressions embedded in the Svelte syntax
  • e.g. expressions inside of {}, event bindings on:click="", and more

How to use in VS Code and Atom

This plugin comes with Svelte for VS Code and Svelte for Atom so just install the extension for your favorite editor and enjoy.

If you want to customize some formatting behavior, see section "Options" below.

Some of the extensions let you define options through extension-specific configuration. These settings are ignored however if there's any configuration file (.prettierrc for example) present.

How to install manually

npm i --save-dev prettier-plugin-svelte prettier

How to use (CLI)

Install prettier and prettier-plugin-svelte as dev dependencies in your project.

Then format your code using Prettier CLI. You may need to add --plugin-search-dir=.

prettier --write --plugin-search-dir=. ./**/*.html

If you want to customize some formatting behavior, see section "Options" below.

Options

Configurations are optional

Make a .prettierrc file in your project directory (Read more about prettier config files here) and add your preferred configuration options. When using Prettier through the CLI, you can also pass options through CLI flags, but a .prettierrc file is recommended.

Svelte Sort Order

Sort order for svelte:options, scripts, markup, and styles.

Format: join the keywords options, scripts, markup, styles with a - in the order you want.

Default	CLI Override	API Override
options-scripts-markup-styles	--svelte-sort-order <string>	svelteSortOrder: <string>

The options order option only exists since version 2. If you use version 1 of prettier-plugin-svelte, omit that option (so for example only write scripts-markup-styles).

Svelte Strict Mode

More strict HTML syntax: less self-closed tags, quotes in attributes, no attribute shorthand (overrules svelteAllowShorthand).

Example:

<!-- svelteStrictMode: true -->
<div foo="{bar}"></div>

<!-- svelteStrictMode: false -->
<div foo={bar} />

Default	CLI Override	API Override
false	--svelte-strict-mode <bool>	svelteStrictMode: <bool>

Svelte Allow Shorthand

Option to enable/disable component attribute shorthand if attribute name and expression are same.

Example:

<!-- allowShorthand: true -->
<input type="text" {value} />

<!-- allowShorthand: false -->
<input type="text" value={value} />

Default	CLI Override	API Override
true	--svelte-allow-shorthand <bool>	svelteAllowShorthand: <bool>

Svelte Bracket New Line

Put the > of a multiline element on a new line. Roughly the Svelte equivalent of the jsxBracketSameLine rule. Setting this to false will have no effect for whitespace-sensitive tags (inline elements) when there's no whitespace between the > of the start tag and the inner content, or when there's no whitespace after the > of the end tag.

Example:

<!-- before formatting -->
<span><div>foo</div><span>bar</span></span>
<div pretend break>content</div>

<!-- after formatting, svelteBracketNewLine true -->
<span
    ><div>foo</div>
    <span>bar</span></span
>
<div
     pretend
     break
>
    content
</div>

<!-- after formatting, svelteBracketNewLine false -->
<span
    ><div>foo</div>
    <span>bar</span></span>
<div
     pretend
     break>
    content
</div>

Default	CLI Override	API Override
true	--svelte-bracket-new-line <bool>	svelteBracketNewLine: <bool>

Svelte Indent Script And Style

Whether or not to indent the code inside <script> and <style> tags in Svelte files. This saves an indentation level, but might break code folding in your editor.

Default	CLI Override	API Override
true	--svelte-indent-script-and-style <bool>	svelteIndentScriptAndStyle: <bool>

.prettierrc example

{
  "svelteSortOrder" : "options-styles-scripts-markup",
  "svelteStrictMode": true,
  "svelteBracketNewLine": false,
  "svelteAllowShorthand": false,
  "svelteIndentScriptAndStyle": false
}

Changelog

2.3.1

• (fix) More robust check for hardline to prevent trailing empty lines in <style>/<script> tags (#222)