ESLintの導入

eslint-config-preactがjestの設定に依存していて、その中のひとつがjestのバージョンを読もうとする。
今回は入れないのでdisableにする。
preactjs/eslint-config-preact#19
jest-community/eslint-plugin-jest#686

.eslintrc.json

@@ -0,0 +1,23 @@
+{
+  "env": {
+    "browser": true,
+    "es2021": true
+  },
+  "extends": [
+    "eslint:recommended",
+    "plugin:@typescript-eslint/recommended",
+    "preact",
+    "prettier"
+  ],
+  "parser": "@typescript-eslint/parser",
+  "parserOptions": {
+    "ecmaVersion": "latest",
+    "sourceType": "module"
+  },
+  "plugins": [
+    "@typescript-eslint"
+  ],
+  "rules": {
+    "jest/no-deprecated-functions": 0
+  }
+}

package.json

@@ -7,15 +7,20 @@
     "dev": "vite",
     "build": "tsc && vite build",
     "preview": "vite preview",
-    "format": "prettier . --write"
+    "format": "prettier . --write",
+    "lint": "eslint . --fix"
   },
   "dependencies": {
     "preact": "^10.11.3"
   },
   "devDependencies": {
     "@preact/preset-vite": "^2.5.0",
+    "@typescript-eslint/eslint-plugin": "^6.1.0",
+    "@typescript-eslint/parser": "^6.1.0",
+    "eslint": "^8.45.0",
+    "eslint-config-preact": "^1.3.0",
     "prettier": "^3.0.0",
     "typescript": "^4.9.3",
     "vite": "^4.1.0"
   }
-}
+}