Upgrade to eslint v9

eslint.config.js

@@ -0,0 +1,377 @@
+import js from "@eslint/js";
+import globals from "globals";
+import stylistic from '@stylistic/eslint-plugin';
+
+export default [
+  {
+    ignores: [
+      "**/*.{js,cjs}",
+      "!lib/ical/**/*.{js,cjs}",
+      "!test/**/*.{js,cjs}",
+      "!tools/scriptutils.js",
+      "!eslint.config.js",
+      "!rollup.config.js",
+      "!karma.conf.cjs"
+    ]
+  },
+  js.configs.recommended,
+  {
+    plugins: {
+      "@stylistic": stylistic
+    },
+    languageOptions: {
+      globals: {
+        ...globals.es2021
+      }
+    },
+    rules: {
+      // Enforce one true brace style (opening brace on the same line)
+      // Allow single line (for now) because of the vast number of changes needed
+      "@stylistic/brace-style": ["error", "1tbs", { allowSingleLine: true }],
+
+      // Enforce newline at the end of file, with no multiple empty lines.
+      "@stylistic/eol-last": "error",
+
+      // Disallow using variables outside the blocks they are defined
+      //"block-scoped-var": "error",
+
+      // Allow trailing commas for easy list extension.  Having them does not
+      // impair readability, but also not required either.
+      "@stylistic/comma-dangle": 0,
+
+      // Enforce spacing before and after comma
+      "@stylistic/comma-spacing": ["error", { before: false, after: true }],
+
+      // Enforce one true comma style.
+      "@stylistic/comma-style": ["error", "last"],
+
+      // Enforce curly brace conventions for all control statements.
+      //"curly": "error",
+
+      // Enforce the spacing around the * in generator functions.
+      "@stylistic/generator-star-spacing": ["error", "after"],
+
+      // Require space before/after arrow function's arrow
+      "@stylistic/arrow-spacing": ["error", { before: true, after: true }],
+
+      // Enforces spacing between keys and values in object literal properties.
+      "@stylistic/key-spacing": ["error", { beforeColon: false, afterColon: true, mode: "minimum" }],
+
+      // Disallow the omission of parentheses when invoking a constructor with no
+      // arguments.
+      "@stylistic/new-parens": "error",
+
+      // Disallow use of the Array constructor.
+      "no-array-constructor": "error",
+
+      // disallow use of the Object constructor
+      "no-object-constructor": "error",
+
+      // Disallow Primitive Wrapper Instances
+      "no-new-wrappers": "error",
+
+      // Disallow adding to native types
+      "no-extend-native": "error",
+
+      // Disallow unnecessary semicolons.
+      "@stylistic/no-extra-semi": "error",
+
+      // Disallow mixed spaces and tabs for indentation.
+      "@stylistic/no-mixed-spaces-and-tabs": "error",
+
+      // Disallow comparisons where both sides are exactly the same.
+      "no-self-compare": "error",
+
+      // Disallow trailing whitespace at the end of lines.
+      "@stylistic/no-trailing-spaces": "error",
+
+      // disallow use of octal escape sequences in string literals, such as
+      // var foo = "Copyright \251";
+      "no-octal-escape": "error",
+
+      // disallow use of void operator
+      "no-void": "error",
+
+      // Disallow Yoda conditions (where literal value comes first).
+      "yoda": "error",
+
+      // Require a space immediately following the // in a line comment.
+      //"spaced-comment": ["error", "always"],
+
+      // Require use of the second argument for parseInt().
+      //"radix": "error",
+
+      // Require spaces before/after unary operators (words on by default,
+      // nonwords off by default).
+      //"space-unary-ops": ["error", { "words": true, "nonwords": false }],
+
+      // Enforce spacing after semicolons.
+      "@stylistic/semi-spacing": ["error", { before: false, after: true }],
+
+      // Disallow the use of Boolean literals in conditional expressions.
+      "no-unneeded-ternary": "error",
+
+      // Disallow use of multiple spaces (sometimes used to align const values,
+      // array or object items, etc.). It's hard to maintain and doesn't add that
+      // much benefit.
+      "@stylistic/no-multi-spaces": "error",
+
+      // Require spaces around operators, except for a|0.
+      // Disabled for now given eslint doesn't support default args yet
+      // "space-infix-ops": ["error", {"int32Hint": true}],
+
+      // Require a space around all keywords.
+      "@stylistic/keyword-spacing": "error",
+
+      // Disallow space between function identifier and application.
+      "@stylistic/func-call-spacing": "error",
+
+      // Disallow use of comma operator.
+      "no-sequences": "error",
+
+      // Disallow use of assignment in return statement. It is preferable for a
+      // single line of code to have only one easily predictable effect.
+      "no-return-assign": "error",
+
+      // Require return statements to either always or never specify values
+      //"consistent-return": "error",
+
+      // Disallow padding within blocks.
+      //"padded-blocks": ["error", "never"],
+
+      // Disallow spaces inside parentheses.
+      "@stylistic/space-in-parens": ["error", "never"],
+
+      // Require space after keyword for anonymous functions, but disallow space
+      // after name of named functions.
+      "@stylistic/space-before-function-paren": ["error", { anonymous: "never", named: "never" }],
+
+      // Always require use of semicolons wherever they are valid.
+      "@stylistic/semi": ["error", "always"],
+
+      // Warn about declaration of variables already declared in the outer scope.
+      "no-shadow": "error",
+
+      // Disallow global and local variables that aren't used, but allow unused function arguments.
+      "no-unused-vars": ["error", { vars: "all", args: "none" }],
+
+      // Require padding inside curly braces
+      "@stylistic/object-curly-spacing": ["error", "always"],
+
+      // Disallow spaces inside of brackets
+      "@stylistic/array-bracket-spacing": ["error", "never"],
+
+      // Disallow constant expressions in conditions
+      //"no-constant-condition": ["error", {"checkLoops": false }],
+
+      // Disallow Regexs That Look Like Division
+      "no-div-regex": "error",
+
+      // Disallow Iterator (using __iterator__)
+      "no-iterator": "error",
+
+      // Enforce consistent linebreak style
+      "@stylistic/linebreak-style": ["error", "unix"],
+
+      // Enforces return statements in callbacks of array's methods
+      "array-callback-return": "error",
+
+      // Disallow duplicate imports
+      "no-duplicate-imports": "error",
+
+      // Disallow Labeled Statements
+      "no-labels": "error",
+
+      // Disallow Multiline Strings
+      "no-multi-str": "error",
+
+      // Disallow Initializing to undefined
+      "no-undef-init": "error",
+
+      // Disallow unnecessary computed property keys on objects
+      "no-useless-computed-key": "error",
+
+      // Disallow unnecessary constructor
+      "no-useless-constructor": "error",
+
+      // Disallow renaming import, export, and destructured assignments to the
+      // same name
+      "no-useless-rename": "error",
+
+      // Enforce spacing between rest and spread operators and their expressions
+      "@stylistic/rest-spread-spacing": ["error", "never"],
+
+      // Disallow usage of spacing in template string expressions
+      "@stylistic/template-curly-spacing": ["error", "never"],
+
+      // Disallow the Unicode Byte Order Mark
+      "unicode-bom": ["error", "never"],
+
+      // Enforce spacing around the * in yield* expressions
+      "@stylistic/yield-star-spacing": ["error", "after"],
+
+      // Disallow Implied eval
+      "no-implied-eval": "error",
+
+      // Disallow unnecessary function binding
+      "no-extra-bind": "error",
+
+      // Disallow new For Side Effects
+      "no-new": "error",
+
+      // Require IIFEs to be Wrapped
+      //"wrap-iife": ["error", "inside"],
+
+      // Disallow Unused Expressions
+      "no-unused-expressions": "error",
+
+      // Disallow function or var declarations in nested blocks
+      "no-inner-declarations": "error",
+
+      // Enforce newline before and after dot
+      "@stylistic/dot-location": ["error", "property"],
+
+      // Disallow Use of caller/callee
+      "no-caller": "error",
+
+      // Disallow Floating Decimals
+      "@stylistic/no-floating-decimal": "error",
+
+      // Require Space Before Blocks
+      "@stylistic/space-before-blocks": "error",
+
+      // Operators always before the line break
+      "@stylistic/operator-linebreak": ["error", "after", { overrides: { ":": "before", "?": "ignore" } }],
+
+      // Restricts the use of parentheses to only where they are necessary
+      //"no-extra-parens": ["error", "all", { "conditionalAssign": false, "returnAssign": false, "nestedBinaryExpressions": false }],
+
+      // Disallow if as the only statement in an else block.
+      //"no-lonely-if": "error",
+
+      // Not more than two empty lines with in the file, and no extra lines at
+      // beginning or end of file.
+      "@stylistic/no-multiple-empty-lines": ["error", { max: 2, maxEOF: 0, maxBOF: 0 }],
+
+      // Make sure all setters have a corresponding getter
+      "accessor-pairs": "error",
+
+      // Enforce spaces inside of single line blocks
+      //"block-spacing": ["error", "always"],
+
+      // Disallow spaces inside of computed properties
+      "@stylistic/computed-property-spacing": ["error", "never"],
+
+      // Require consistent this (using |self|)
+      "consistent-this": ["error", "self"],
+
+      // Disallow unnecessary .call() and .apply()
+      "no-useless-call": "error",
+
+      // Require dot notation when accessing properties
+      "dot-notation": "error",
+
+      // Disallow named function expressions
+      //"func-names": ["error", "never"],
+
+      // Enforce placing object properties on separate lines
+      "@stylistic/object-property-newline": ["error", { allowMultiplePropertiesPerLine: true }],
+
+      // Enforce consistent line breaks inside braces
+      //"object-curly-newline": ["error", { "multiline": true }],
+
+      // Disallow whitespace before properties
+      "@stylistic/no-whitespace-before-property": "error",
+
+      // Disallow mixes of different operators, but allow simple math operations.
+      //"no-mixed-operators": ["error", {
+      //    "groups": [
+      //        /* ["+", "-", "*", "/", "%", "**"], */
+      //        ["&", "|", "^", "~", "<<", ">>", ">>>"],
+      //        ["==", "!=", "===", "!==", ">", ">=", "<", "<="],
+      //        ["&&", "||"],
+      //        ["in", "instanceof"]
+      //    ]
+      //}],
+
+      // Disallow unnecessary concatenation of strings
+      "no-useless-concat": "error",
+
+      // Disallow unmodified conditions of loops
+      //"no-unmodified-loop-condition": "error",
+
+      // Suggest using arrow functions as callbacks
+      //"prefer-arrow-callback": ["error", { "allowNamedFunctions": true }],
+
+      // Suggest using the spread operator instead of .apply()
+      "prefer-spread": "error",
+
+      // Quoting style for property names
+      //"@stylistic/quote-props": ["error", "consistent-as-needed", { "keywords": true }],
+
+      // Disallow negated conditions
+      //"no-negated-condition": "error",
+
+      // Enforce a maximum number of statements allowed per line
+      "@stylistic/max-statements-per-line": ["error", { max: 2 }],
+
+      // Disallow arrow functions where they could be confused with comparisons
+      "@stylistic/no-confusing-arrow": "error",
+
+      // Disallow Unnecessary Nested Blocks
+      "no-lone-blocks": "error",
+
+      // Enforce consistent indentation (2-space)
+      //"indent": ["error", 2, { "SwitchCase": 1 }],
+
+      // Disallow var, use let or const instead
+      "no-var": "error"
+    }
+  },
+  {
+    files: ["test/**/*.js"],
+    languageOptions: {
+      globals: {
+        ...globals.mocha,
+        ...globals.node,
+        ICAL: "readonly",
+        assert: "readonly",
+        testSupport: "readonly",
+        perfTest: "readonly"
+      }
+    }
+  },
+  {
+    files: ["test/performance/**/*.js"],
+    languageOptions: {
+      globals: {
+        perfCompareSuite: "readonly"
+      }
+    }
+  },
+  {
+    files: ["test/support/helper.js"],
+    languageOptions: {
+      globals: {
+        ...globals.browser,
+        ...globals.node,
+        ...globals.mocha
+      }
+    }
+  },
+  {
+    files: ["tools/scriptutils.js", "test/support/perfReporter.cjs", "karma.conf.cjs"],
+    languageOptions: {
+      globals: globals.node
+    }
+  },
+  {
+    files: ["eslint.config.js"],
+    plugins: {
+      "@stylistic": stylistic
+    },
+    rules: {
+      "@stylistic/quote-props": ["error", "consistent-as-needed"]
+    }
+  }
+];

karma.conf.cjs

@@ -12,9 +12,9 @@ module.exports = function(config) {
       { pattern: 'samples/**/*.ics', included: false },
       { pattern: 'test/parser/*', included: false },
       { pattern: 'lib/ical/*.js', type: 'module', included: false },
-      { pattern: 'test/*_test.js', included: false  },
-      { pattern: 'test/acceptance/*_test.js', included: false  },
-      { pattern: 'test/support/helper.js', type: "module", included: true  },
+      { pattern: 'test/*_test.js', included: false },
+      { pattern: 'test/acceptance/*_test.js', included: false },
+      { pattern: 'test/support/helper.js', type: "module", included: true },
     ],
     client: { mocha: Object.assign(pkg.mocha, { timeout: 0 }) },
     reporters: ['spec'],