Linting: StandardJS for src/, test/; Prettier for types/ (#2544)

* setup linting with eslint-config-standard, prettier

* [autofix] npm run lint -- --fix with new setup

* [manual] fix types/ directory errors

* [manual] fix linting errors in test/ directory

* [manual] fix single linting error in src/

* revert ts-expect-error comment change

* error on .only in mocha tests

* fix test description typo

* move some short objects to single line

* add and gitignore eslintcache

* individually suppress ts any

* set --max-warnings to 0

* extract matrices to constants

* update ts-expect-error comments

Author: ChristopherChudzicki

.eslintrc.cjs

@@ -0,0 +1,55 @@
+module.exports = {
+  env: {
+    browser: true,
+    es2021: true,
+    node: true
+  },
+  extends: ['eslint:recommended'],
+  parserOptions: {
+    ecmaVersion: 12,
+    sourceType: 'module'
+  },
+  ignorePatterns: ['*.generated.js'],
+  rules: {},
+  overrides: [
+    {
+      files: ['*.js', '*.cjs', '*.mjs'],
+      extends: [
+        'standard'
+      ]
+    },
+    {
+      files: ['*.test.js'],
+      plugins: ['mocha'],
+      extends: [
+        'standard',
+        'plugin:mocha/recommended'
+      ],
+      rules: {
+        'mocha/no-skipped-tests': 'error',
+        'mocha/no-exclusive-tests': 'error',
+        'mocha/no-setup-in-describe': 'off',
+        'mocha/no-identical-title': 'off' // TODO: Remove this
+      }
+    },
+    {
+      files: ['types/*.ts'],
+      extends: [
+        'plugin:@typescript-eslint/recommended',
+        'plugin:prettier/recommended' // this should come last
+      ],
+      rules: {
+        '@typescript-eslint/no-unused-vars': [
+          'error',
+          { argsIgnorePattern: '^_', varsIgnorePattern: '^_' }
+        ]
+      },
+      plugins: ['@typescript-eslint'],
+      parserOptions: {
+        ecmaVersion: 12,
+        sourceType: 'module',
+        project: 'types/tsconfig.json'
+      }
+    }
+  ]
+}

.gitignore

@@ -9,6 +9,7 @@ _site
 node_modules
 .nyc_output
 /coverage
+.eslintcache
 
 lib
 *.generated.js

.prettierrc.cjs

@@ -0,0 +1,4 @@
+module.exports = {
+  semi: false,
+  singleQuote: true,
+}