Update ESLint and simplify its configs (#568)

* refactor: Convert ESLint config files to YAML

This allows for the config files to be commented.

* chore: Update eslint to v4

* refactor: Add a root tsconfig.json

As the individual package tsconfigs can extend the root, this allows
for common options to be centrally controlled, as well as making it
easier to enable dev tools to be automatically properly configured.

* style: Satisfy updated lint rules

* refactor: Merge ESLint configs into .eslintrc.yaml & eslint-base.yaml

* refactor: Move @babel/eslint-parser dependency & config to fluent-react

Author: eemeli

.eslintrc.yaml

@@ -0,0 +1,45 @@
+root: true
+
+env:
+  es6: true
+
+overrides:
+  - files: ["*/src/*.js"]
+    extends:
+      - ./eslint-base.yaml
+    parserOptions:
+      ecmaVersion: 9
+      sourceType: module
+
+  - files: ["*/src/*.ts"]
+    parser: "@typescript-eslint/parser"
+    parserOptions:
+      project: ./tsconfig.json
+    extends:
+      - eslint:recommended
+      - ./eslint-base.yaml
+      - plugin:@typescript-eslint/recommended
+      - plugin:@typescript-eslint/recommended-requiring-type-checking
+    rules:
+      complexity: off
+      prefer-const: off
+      no-undef: off
+      no-unused-vars: [error, args: none]
+      no-use-before-define: off
+      "@typescript-eslint/no-inferrable-types": off
+      "@typescript-eslint/no-unused-vars": [error, args: none]
+      "@typescript-eslint/no-use-before-define": off
+      "@typescript-eslint/explicit-function-return-type": error
+
+  - files: ["*/test/**"]
+    parserOptions:
+      ecmaVersion: 2020 # Required by import.meta
+      sourceType: module
+    env:
+      node: true
+      mocha: true
+    plugins:
+      - mocha
+    rules:
+      mocha/no-exclusive-tests: error
+      mocha/no-identical-title: error

eslint-base.yaml

@@ -0,0 +1,72 @@
+rules:
+  valid-typeof: 2
+  no-console: 1
+  no-dupe-args: 2
+  no-dupe-keys: 2
+  no-duplicate-case: 2
+  no-extra-semi: 1
+  no-func-assign: 2
+  func-call-spacing: [2, never]
+  no-unreachable: 1
+  no-unexpected-multiline: 2
+  no-sparse-arrays: 2
+  dot-location: [2, property]
+  no-implied-eval: 2
+  no-loop-func: 2
+  no-useless-call: 2
+  no-useless-concat: 2
+  no-delete-var: 2
+  no-shadow: 2
+  no-undef: 2
+  no-undef-init: 2
+  no-unused-vars: 1
+  consistent-return: 1
+  curly: [2, multi-line]
+  eqeqeq: 2
+  no-extend-native: 2
+  no-global-assign: 2
+  no-extra-bind: 2
+  array-bracket-spacing: 2
+  brace-style: [1, 1tbs]
+  no-mixed-spaces-and-tabs: 2
+  no-tabs: 2
+  prefer-arrow-callback: 1
+  prefer-template: 2
+  prefer-spread: 2
+  quotes: [2, double, avoidEscape: true]
+  max-depth: [2, 6]
+  max-len: [2, 80]
+  no-nested-ternary: 2
+  no-unneeded-ternary: 2
+  strict: [2, global]
+  indent: [2, 2, SwitchCase: 1]
+  no-useless-escape: 2
+  no-duplicate-imports: 2
+  no-unsafe-negation: 2
+  no-use-before-define: [2, { functions: false, classes: false }]
+  space-infix-ops: 2
+  no-constant-condition: [1, checkLoops: false]
+  no-empty: 1
+  use-isnan: 2
+  dot-notation: 2
+  no-caller: 2
+  no-else-return: 2
+  no-eval: 2
+  no-implicit-globals: 2
+  no-iterator: 2
+  no-multi-spaces: 2
+  no-multi-str: 2
+  no-octal: 2
+  no-proto: 2
+  no-sequences: 2
+  block-spacing: 2
+  eol-last: 2
+  key-spacing: 2
+  no-trailing-spaces: 2
+  prefer-rest-params: 2
+  no-cond-assign: 2
+  keyword-spacing: 2
+  arrow-parens: [2, as-needed]
+  no-useless-return: 2
+  semi: 2
+  spaced-comment: [2, always]

eslint_js.json

@@ -4,8 +4,7 @@ GLOBAL  := FluentBundle
 include ../common.mk
 
 lint:
-	@$(ESLINT) --config $(ROOT)/eslint_ts.json --max-warnings 0 src/*.ts
-	@$(ESLINT) --config $(ROOT)/eslint_test.json --max-warnings 0 test/
+	@$(ESLINT) --max-warnings 0 src/ test/
 	@echo -e " $(OK) lint"
 
 .PHONY: compile

eslint_test.json

@@ -22,7 +22,7 @@ function values(
   opts: Record<string, FluentValue>,
   allowed: Array<string>
 ): Record<string, unknown> {
-  const unwrapped: Record<string, unknown> = Object.create(null);
+  const unwrapped = Object.create(null) as Record<string, unknown>;
   for (const [name, opt] of Object.entries(opts)) {
     if (allowed.includes(name)) {
       unwrapped[name] = opt.valueOf();

eslint_ts.json

@@ -22,7 +22,12 @@ export class FluentBundle {
   public _functions: Record<string, FluentFunction>;
   public _useIsolating: boolean;
   public _transform: TextTransform;
-  public _intls: WeakMap<object, Record<string, object>> = new WeakMap();
+  public _intls = new WeakMap<
+    | typeof Intl.NumberFormat
+    | typeof Intl.DateTimeFormat
+    | typeof Intl.PluralRules,
+    Record<string, Intl.NumberFormat | Intl.DateTimeFormat | Intl.PluralRules>
+  >();
 
   /**
    * Create an instance of `FluentBundle`.

fluent-bundle/makefile

@@ -111,7 +111,7 @@ function getArguments(
   args: Array<Expression | NamedArgument>
 ): Arguments {
   const positional: Array<FluentValue> = [];
-  const named: Record<string, FluentValue> = Object.create(null);
+  const named = Object.create(null) as Record<string, FluentValue>;
 
   for (const arg of args) {
     if (arg.type === "narg") {

fluent-bundle/src/builtins.ts

@@ -179,7 +179,7 @@ export class FluentResource {
     }
 
     function parseAttributes(): Record<string, Pattern> {
-      let attrs: Record<string, Pattern> = Object.create(null);
+      let attrs = Object.create(null) as Record<string, Pattern>;
 
       while (test(RE_ATTRIBUTE_START)) {
         let name = match1(RE_ATTRIBUTE_START);