Add ESLint and Prettier with consistent formatting standards

- Add ESLint 9 and Prettier for consistent code formatting across docs repos
- Configure ESLint with TypeScript and Astro support
- Standardize lint and format commands across all repositories
- Upgrade to ESLint 9 flat config format (eslint.config.js)
- Update all ESLint and Prettier packages to latest versions
- Add CI checks to enforce formatting standards

Author: JonathanMatthey

.github/pull_request_template.md

@@ -0,0 +1,19 @@
+## Changes proposed in this pull request
+
+<!--
+Provide a succinct description of what this pull request entails.
+-->
+
+## Context
+
+<!--
+What were you trying to do?
+Link issues here -  using `fixes #number`
+-->
+
+## Checklist
+
+- [ ] I have run `bun run format` to ensure code is properly formatted
+- [ ] I have verified that `bun run lint` passes without errors
+
+

.github/workflows/lint.yml

@@ -0,0 +1,23 @@
+name: Lint
+
+on:
+  pull_request:
+    branches:
+      - main
+  push:
+    branches:
+      - main
+
+jobs:
+  lint:
+    name: Run ESLint
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: oven-sh/setup-bun@v1
+      - name: Install dependencies
+        run: bun install
+      - name: Run ESLint
+        run: bun run lint
+
+

README.md

@@ -60,3 +60,17 @@ git clone https://github.com/interledger/docs-styleguide.git
 ```
 
 3. After you're done with your changes and have tested that all is well, feel free to make a pull request and it will get reviewed, and hopefully merged into the source code. The version will get bumped and all the sites will have to make an update to their dependencies as well.
+
+### 🔍 Code Linting
+
+This project uses [ESLint](https://eslint.org/) for code linting. Before submitting a pull request, please ensure your code passes linting:
+
+1. **Fix issues**: Run `bun run format` to automatically fix linting issues
+2. **Check before pushing**: Run `bun run lint` to verify everything passes (CI will also run this)
+
+ESLint is configured to work with TypeScript and Astro files. The configuration extends recommended rules from ESLint, TypeScript ESLint, and Astro ESLint plugins.
+
+| Command          | Action                            |
+| :--------------- | :-------------------------------- |
+| `bun run format` | Fix linting issues                 |
+| `bun run lint`   | Check linting                      |

bun.lock

@@ -0,0 +1,63 @@
+import eslintPluginAstro from "eslint-plugin-astro";
+import tseslintPlugin from "@typescript-eslint/eslint-plugin";
+import tsparser from "@typescript-eslint/parser";
+import js from "@eslint/js";
+import globals from "globals";
+
+export default [
+  {
+    ignores: ["node_modules", "dist", ".astro", "*.d.ts"]
+  },
+  js.configs.recommended,
+  {
+    files: ["**/*.{js,mjs,ts,tsx}"],
+    languageOptions: {
+      globals: {
+        ...globals.node,
+        ...globals.browser
+      },
+      parser: tsparser,
+      parserOptions: {
+        ecmaVersion: 2022,
+        sourceType: "module"
+      }
+    },
+    plugins: {
+      "@typescript-eslint": tseslintPlugin
+    },
+    rules: {
+      ...tseslintPlugin.configs.recommended.rules,
+      "@typescript-eslint/no-unused-vars": [
+        "error",
+        {
+          argsIgnorePattern: "^_",
+          varsIgnorePattern: "^_"
+        }
+      ],
+      "@typescript-eslint/no-explicit-any": "warn"
+    }
+  },
+  {
+    files: ["*.d.ts"],
+    rules: {
+      "@typescript-eslint/triple-slash-reference": "off"
+    }
+  },
+  {
+    files: ["*.astro"],
+    plugins: {
+      astro: eslintPluginAstro
+    },
+    languageOptions: {
+      parser: eslintPluginAstro.parser,
+      parserOptions: {
+        parser: tsparser,
+        extraFileExtensions: [".astro"]
+      }
+    },
+    rules: {
+      ...eslintPluginAstro.configs.recommended.rules
+    }
+  }
+];
+

eslint.config.js

@@ -11,7 +11,9 @@
     "index.ts"
   ],
   "scripts": {
-    "test": "echo \"Error: no test specified\" && exit 1"
+    "test": "echo \"Error: no test specified\" && exit 1",
+    "format": "eslint . --fix",
+    "lint": "eslint ."
   },
   "author": "Interledger <tech@interledger.org>",
   "license": "ISC",
@@ -21,5 +23,14 @@
   },
   "dependencies": {
     "mermaid": "^11.8.0"
+  },
+  "devDependencies": {
+    "@eslint/js": "^9.32.0",
+    "@typescript-eslint/eslint-plugin": "^8.39.0",
+    "@typescript-eslint/parser": "^8.39.0",
+    "astro-eslint-parser": "^1.2.2",
+    "eslint": "^9.32.0",
+    "eslint-plugin-astro": "^1.3.1",
+    "globals": "^16.3.0"
   }
 }

package.json

@@ -67,7 +67,7 @@ button:hover span {
     const url = URL.createObjectURL(blob)
     const win = open(url)
     if (win) {
-      win.onload = (event) => URL.revokeObjectURL(url);
+      win.onload = (_event) => URL.revokeObjectURL(url);
     }
   }