build: Add eslint

These changes introduce ESLint configuration to the project,
establishing standardized code quality and style guidelines.  The
`eslint.config.mjs` file defines rules for JavaScript, HTML, and Twig
files, ensuring code consistency and maintainability.

Here's a breakdown of the key aspects:

- **ESLint Integration:** The primary change is the introduction of
ESLint rules. ESLint helps enforce consistent coding styles and
identifies potential errors.
- **Rule Configuration:** The `eslint.config.mjs` file specifies various
ESLint rules for JavaScript, HTML, and Twig files, such as brace style,
indentation, and semicolon usage.
- **Global Declarations:**  The ESLint configuration explicitly defines
global variables, clarifying their usage and preventing unintended
conflicts.
- **Code Style Enforcement:** This setup enforces consistent code style
across the project, making code easier to read and understand.
- **Error Detection:** ESLint helps identify potential code issues early
on, reducing the chances of runtime errors and improving code quality.
- All current issues have been identified and fixed inside the codebase.

Additionally, the changes to `main.js` illustrate the application of
ESLint rules to existing code. The `no-unused-vars` rule is enabled,
helping ensure that all variables are used within their scope. This
change helps maintain code clarity and reduce clutter.

Overall, these changes represent a significant step towards establishing
a robust code quality and style framework for the project.

Author: MikeRatcliffe

eslint.config.mjs

@@ -0,0 +1,167 @@
+import eslintConfigPrettier from "eslint-config-prettier";
+import globals from "globals";
+import html from "eslint-plugin-html";
+import json from "eslint-plugin-json";
+import pluginJs from "@eslint/js";
+import stylisticJs from "@stylistic/eslint-plugin-js";
+
+export default [
+  pluginJs.configs.recommended,
+  eslintConfigPrettier,
+  {
+    files: ["**/*.js", "**/*.html", "**/*.twig"],
+    languageOptions: {
+      ecmaVersion: "latest",
+      sourceType: "commonjs",
+      globals: {
+        ...globals.browser,
+        ...globals.commonjs,
+        ...globals.node,
+        $: "readonly",
+        $id: "readonly",
+        arch: "readonly",
+        checkMount: "readonly",
+        dialog: "readonly",
+        formatBytes: "readonly",
+        formatEta: "readonly",
+        hash_alg: "readonly",
+        id: "readonly",
+        ipcRenderer: "readonly",
+        loadInclude: "readonly",
+        path: "readonly",
+        platform: "readonly",
+        remote: "readonly",
+        shell: "readonly",
+        sidenoderHome: "readonly",
+        version: "readonly",
+        win: "readonly",
+      },
+    },
+    plugins: {
+      html,
+      "@stylistic/js": stylisticJs,
+    },
+    rules: {
+      "@stylistic/js/brace-style": [
+        "error",
+        "1tbs",
+        { allowSingleLine: false },
+      ],
+      "@stylistic/js/indent": [
+        "error",
+        2,
+        {
+          ignoredNodes: ["TemplateLiteral"],
+          SwitchCase: 1,
+        },
+      ],
+      "@stylistic/js/no-mixed-spaces-and-tabs": ["error"],
+      "@stylistic/js/semi": ["error", "always"],
+      "constructor-super": ["error"],
+      curly: ["error", "all"],
+      eqeqeq: ["error", "always"],
+      "for-direction": ["error"],
+      "getter-return": ["error"],
+      "no-async-promise-executor": ["error"],
+      "no-case-declarations": ["error"],
+      "no-class-assign": ["error"],
+      "no-compare-neg-zero": ["error"],
+      "no-cond-assign": ["error"],
+      "no-const-assign": ["error"],
+      "no-constant-condition": ["error"],
+      "no-control-regex": ["error"],
+      "no-debugger": ["error"],
+      "no-delete-var": ["error"],
+      "no-dupe-args": ["error"],
+      "no-dupe-class-members": ["error"],
+      "no-dupe-else-if": ["error"],
+      "no-dupe-keys": ["error"],
+      "no-duplicate-case": ["error"],
+      "no-else-return": ["error"],
+      "no-empty": ["error"],
+      "no-empty-character-class": ["error"],
+      "no-empty-pattern": ["error"],
+      "no-ex-assign": ["error"],
+      "no-extra-boolean-cast": ["off"],
+      "no-fallthrough": ["error"],
+      "no-func-assign": ["error"],
+      "no-global-assign": ["error"],
+      "no-import-assign": ["error"],
+      "no-inner-declarations": ["off"],
+      "no-invalid-regexp": ["error"],
+      "no-irregular-whitespace": ["error"],
+      "no-loss-of-precision": ["error"],
+      "no-misleading-character-class": ["error"],
+      "no-nonoctal-decimal-escape": ["error"],
+      "no-obj-calls": ["error"],
+      "no-octal": ["error"],
+      "no-prototype-builtins": ["error"],
+      "no-redeclare": ["error"],
+      "no-regex-spaces": ["error"],
+      "no-self-assign": ["error"],
+      "no-setter-return": ["error"],
+      "no-shadow-restricted-names": ["error"],
+      "no-sparse-arrays": ["error"],
+      "no-this-before-super": ["error"],
+      "no-undef": ["error"],
+      "no-unexpected-multiline": ["error"],
+      "no-unreachable": ["error"],
+      "no-unsafe-finally": ["error"],
+      "no-unsafe-negation": ["error"],
+      "no-unsafe-optional-chaining": ["error"],
+      "no-unused-labels": ["error"],
+      "no-unused-vars": [
+        "error",
+        {
+          argsIgnorePattern: "^_",
+          caughtErrors: "all",
+          caughtErrorsIgnorePattern: "^_",
+        },
+      ],
+      "no-use-before-define": [
+        "error",
+        {
+          functions: false,
+          classes: true,
+          variables: true,
+          allowNamedExports: true,
+        },
+      ],
+      "no-useless-backreference": ["error"],
+      "no-useless-catch": ["error"],
+      "no-useless-escape": ["error"],
+      "no-var": ["error"],
+      "no-with": ["error"],
+      "prefer-const": [
+        "error",
+        {
+          destructuring: "all",
+        },
+      ],
+      "prefer-regex-literals": ["error"],
+      "prefer-template": ["error"],
+      "require-yield": ["error"],
+      "use-isnan": ["error"],
+      "valid-typeof": ["error"],
+    },
+  },
+  {
+    files: ["**/*.mjs"],
+    languageOptions: {
+      sourceType: "module",
+    },
+  },
+  {
+    files: ["**/*.json"],
+    plugins: {
+      json,
+    },
+    processor: json.processors[".json"],
+    rules: {
+      ...json.configs.recommended.rules,
+    },
+  },
+  {
+    ignores: ["**/node_modules/**", "**/*.min.js", "**/modernizr.custom.js"],
+  },
+];