install prettier

.eslintrc.js

@@ -1,6 +1,6 @@
 module.exports = {
 	root: true,
-	extends: '@sveltejs',
+	extends: ['@sveltejs', 'prettier'],
 	settings: {
 		'import/core-modules': [
 			'svelte',

.github/workflows/ci.yml

@@ -44,7 +44,7 @@ jobs:
         with:
           node-version: 16
           cache: pnpm
-      - run: 'pnpm i && pnpm lint'
+      - run: 'pnpm i && pnpm format:check && pnpm lint'
   Unit:
     runs-on: ${{ matrix.os }}
     timeout-minutes: 10

.prettierignore

@@ -0,0 +1,13 @@
+/*
+!/elements
+!/scripts
+# TODO: after launch new site, format site dir.
+/site
+!/src
+src/compiler/compile/internal_exports.ts
+!/test
+/test/**/*.svelte
+/test/**/_expected*
+/test/**/_actual*
+/test/**/expected*
+/types

.prettierrc

@@ -0,0 +1,16 @@
+{
+	"useTabs": true,
+	"singleQuote": true,
+	"trailingComma": "none",
+	"printWidth": 100,
+	"plugins": ["prettier-plugin-svelte"],
+	"overrides": [
+		{
+			"files": "site/**/*.md",
+			"options": {
+				"requirePragma": true
+			}
+		}
+	],
+	"pluginSearchDirs": ["."]
+}

package.json

@@ -81,6 +81,8 @@
   },
   "types": "types/runtime/index.d.ts",
   "scripts": {
+    "format:fix": "prettier . --cache --plugin-search-dir=. --write",
+    "format:check": "prettier . --cache --plugin-search-dir=. --check",
     "test": "npm run test:unit && npm run test:integration && echo \"manually check that there are no type errors in test/types by opening the files in there\"",
     "test:integration": "mocha --exit",
     "test:unit": "mocha --config .mocharc.unit.js --exit",
@@ -133,6 +135,7 @@
     "code-red": "^1.0.0",
     "css-tree": "^2.3.1",
     "eslint": "^8.35.0",
+    "eslint-config-prettier": "^8.8.0",
     "eslint-plugin-import": "^2.27.5",
     "eslint-plugin-svelte3": "^4.0.0",
     "estree-walker": "^3.0.3",
@@ -143,6 +146,8 @@
     "magic-string": "^0.30.0",
     "mocha": "^10.2.0",
     "periscopic": "^3.1.0",
+    "prettier": "^2.8.8",
+    "prettier-plugin-svelte": "^2.10.0",
     "puppeteer": "^19.8.5",
     "rollup": "^3.20.2",
     "source-map": "^0.7.4",

pnpm-lock.yaml

@@ -70,6 +70,9 @@ devDependencies:
   eslint:
     specifier: ^8.35.0
     version: 8.35.0
+  eslint-config-prettier:
+    specifier: ^8.8.0
+    version: 8.8.0(eslint@8.35.0)
   eslint-plugin-import:
     specifier: ^2.27.5
     version: 2.27.5(@typescript-eslint/parser@5.58.0)(eslint@8.35.0)
@@ -100,6 +103,12 @@ devDependencies:
   periscopic:
     specifier: ^3.1.0
     version: 3.1.0
+  prettier:
+    specifier: ^2.8.8
+    version: 2.8.8
+  prettier-plugin-svelte:
+    specifier: ^2.10.0
+    version: 2.10.0(prettier@2.8.8)(svelte@3.58.0)
   puppeteer:
     specifier: ^19.8.5
     version: 19.8.5(typescript@5.0.4)
@@ -1238,6 +1247,15 @@ packages:
       source-map: 0.6.1
     dev: true
 
+  /eslint-config-prettier@8.8.0(eslint@8.35.0):
+    resolution: {integrity: sha512-wLbQiFre3tdGgpDv67NQKnJuTlcUVYHas3k+DZCc2U2BadthoEY4B7hLPvAxaqdyOGCzuLfii2fqGph10va7oA==}
+    hasBin: true
+    peerDependencies:
+      eslint: '>=7.0.0'
+    dependencies:
+      eslint: 8.35.0
+    dev: true
+
   /eslint-import-resolver-node@0.3.7:
     resolution: {integrity: sha512-gozW2blMLJCeFpBwugLTGyvVjNoeo1knonXAcatC6bjPBZitotxdWf7Gimr25N4c0AAOo4eOUfaG82IJPDpqCA==}
     dependencies:
@@ -2552,6 +2570,22 @@ packages:
     engines: {node: '>= 0.8.0'}
     dev: true
 
+  /prettier-plugin-svelte@2.10.0(prettier@2.8.8)(svelte@3.58.0):
+    resolution: {integrity: sha512-GXMY6t86thctyCvQq+jqElO+MKdB09BkL3hexyGP3Oi8XLKRFaJP1ud/xlWCZ9ZIa2BxHka32zhHfcuU+XsRQg==}
+    peerDependencies:
+      prettier: ^1.16.4 || ^2.0.0
+      svelte: ^3.2.0
+    dependencies:
+      prettier: 2.8.8
+      svelte: 3.58.0
+    dev: true
+
+  /prettier@2.8.8:
+    resolution: {integrity: sha512-tdN8qQGvNjw4CHbY+XXk0JgCXn9QiF21a55rBe5LJAU+kDyC4WQn4+awm2Xfk2lQMk5fKup9XgzTZtGkjBdP9Q==}
+    engines: {node: '>=10.13.0'}
+    hasBin: true
+    dev: true
+
   /progress@2.0.3:
     resolution: {integrity: sha512-7PiHtLll5LdnKIMw100I+8xJXR5gW2QwWYkT6iJva0bXitZKa/XMrSbdmg3r2Xnaidz9Qumd0VPaMrZlF9V9sA==}
     engines: {node: '>=0.4.0'}