Build: Update deps, switch to the ESLint flat config

Gruntfile.js

@@ -15,6 +15,7 @@ module.exports = function (grunt) {
         eslint: {
             all: {
                 src: [
+                    '*.mjs',
                     '*.js',
                     'src/*.js',
                 ],

eslint.config.mjs

@@ -0,0 +1,68 @@
+import globals from "globals";
+import eslintConfigMgol from "eslint-config-mgol";
+
+export default [
+    ...eslintConfigMgol,
+    {
+        ignores: [
+            "node_modules/**",
+            "dist/**",
+        ],
+    },
+    {
+        files: [ "*.js" ],
+        languageOptions: {
+            sourceType: "script",
+            globals: {
+                ...globals.node,
+            },
+        },
+        rules: {
+            // Strict mode
+            "strict": ["error", "global"], // "global" in Node, "function" in a browser
+        },
+    },
+    {
+        files: [ "*.mjs" ],
+        languageOptions: {
+            sourceType: "module",
+            globals: {
+                ...globals.node,
+            },
+        },
+    },
+    {
+        files: [ "src/**/*.js" ],
+        languageOptions: {
+            ecmaVersion: 5,
+            sourceType: "script",
+            globals: {
+                ...globals.browser,
+                jQuery: false,
+            },
+        },
+        rules: {
+            // Strict mode
+            "strict": ["error", "function"], // "global" in Node, "function" in a browser
+
+            // Stylistic issues
+            "comma-dangle": ["error", {
+                "arrays": "always-multiline",
+                "objects": "always-multiline",
+                "imports": "always-multiline",
+                "exports": "always-multiline"
+            }],
+            "id-blacklist": ["error", "event"],
+
+            // ECMAScript 6
+            "no-var": "off",
+            "object-shorthand": "off",
+            "prefer-arrow-callback": "off",
+            "prefer-const": "off",
+            "prefer-rest-params": "off",
+            "prefer-spread": "off",
+            "prefer-template": "off",
+            'id-denylist': ['error', 'event'],
+        },
+    },
+];