Add and configure ESLint

.eslintrc.json

@@ -0,0 +1,45 @@
+{
+  "env": {
+    "browser": true,
+    "webextensions": true,
+    "es2021": true
+  },
+  "extends": "eslint:recommended",
+  "parserOptions": {
+    "ecmaVersion": 12,
+    "sourceType": "script"
+  },
+  "root": true,
+  "parser": "@babel/eslint-parser",
+  "rules": {
+    "curly": ["error", "all"],
+    "eqeqeq": ["error", "always"],
+    "indent": [
+      "error",
+      2
+    ],
+    "linebreak-style": [
+      "error",
+      "unix"
+    ],
+    "quotes": [
+      "error",
+      "single"
+    ],
+    "semi": [
+      "error",
+      "never",
+      {
+        "beforeStatementContinuationChars": "never"
+      }
+    ],
+    "strict": [
+      "error",
+      "global"
+    ],
+    "yoda": [
+      "error",
+      "always"
+    ]
+  }
+}

.gitattributes

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+* text=auto
+*.css text eol=lf
+*.editorconfig text eol=lf
+*.html text eol=lf
+*.js text eol=lf
+*.json text eol=lf
+*.md text eol=lf
+*.txt text eol=lf
+*.png binary

.gitignore

@@ -1,2 +1,3 @@
+/node_modules
 /web-ext-artifacts
 /.web-extension-id

package.json

@@ -0,0 +1,8 @@
+{
+  "babel": {},
+  "devDependencies": {
+    "@babel/core": "^7.16.0",
+    "@babel/eslint-parser": "^7.16.0",
+    "eslint": "^8.2.0"
+  }
+}