Add eslint (#20)

.eslintrc.json

@@ -0,0 +1,39 @@
+{
+    "env": {
+        "browser": true,
+        "es2021": true
+    },
+    "extends": [
+        "eslint:recommended",
+        "plugin:@typescript-eslint/recommended"
+    ],
+    "parser": "@typescript-eslint/parser",
+    "parserOptions": {
+        "ecmaVersion": "latest",
+        "sourceType": "module"
+    },
+    "plugins": [
+        "@typescript-eslint"
+    ],
+    "rules": {
+        "indent": [
+            "error",
+            4
+        ],
+        "linebreak-style": [
+            "error",
+            "unix"
+        ],
+        "quotes": [
+            "error",
+            "double"
+        ],
+        "semi": [
+            "error",
+            "always"
+        ]
+    },
+    "globals": {
+        "chrome": "readonly"
+    }    
+}

.github/workflows/eslint.yml

@@ -0,0 +1,21 @@
+name: ESLint Check
+
+on: [push, pull_request]
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Use Node.js
+      uses: actions/setup-node@v2
+      with:
+        node-version: '20'
+
+    - name: Install Dependencies
+      run: npm install
+
+    - name: Run ESLint
+      # run: npx eslint .
+      run: npx eslint "src/**/*.{js,ts}"

.vscode/settings.json

@@ -1,3 +1,7 @@
 {
-  "git-blame.gitWebUrl": ""
-}
+  "git-blame.gitWebUrl": "",
+  "editor.codeActionsOnSave": {
+      "source.fixAll.eslint": true
+  },
+  "eslint.validate": ["javascript"]
+}