Align config with patternslib

.editorconfig

@@ -0,0 +1,12 @@
+[*]
+indent_style = space
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+charset = utf-8
+
+[*.js]
+indent_size = 4
+
+[{*.css,*.scss,*.xml,*.html}]
+indent_size = 2

.eslintrc.js

@@ -0,0 +1,27 @@
+module.exports = {
+    extends: ["eslint:recommended", "prettier"],
+    root: true,
+    env: {
+        es6: "true",
+        browser: true,
+        node: true,
+        jest: true,
+    },
+    parser: "babel-eslint",
+    ignorePatterns: [
+        "src/lib/depends_parse.js",
+        "src/pat/calendar/moment-timezone-with-data-2010-2020.js",
+    ],
+    rules: {
+        "no-debugger": 1,
+        "no-duplicate-imports": 1,
+        // Do keep due avoid unintendet consequences.
+        "no-alert": 0,
+        "no-control-regex": 0,
+        "no-self-assign": 0,
+        "no-useless-escape": 0,
+    },
+    globals: {
+        spyOn: true, // eventually replace with jest.spyOn and then fix a ton of test failures.
+    },
+};

.prettierignore

@@ -0,0 +1,4 @@
+dist/
+node_modules/
+style/
+stats.json

.prettierrc.json

@@ -0,0 +1,4 @@
+{
+    "tabWidth": 4,
+    "quoteProps": "consistent"
+}

babel.config.js

@@ -0,0 +1,12 @@
+module.exports = {
+    presets: [
+        [
+            "@babel/preset-env",
+            {
+                useBuiltIns: "entry",
+                corejs: 3,
+            },
+        ],
+    ],
+    plugins: ["@babel/plugin-proposal-optional-chaining"],
+};

package.json

@@ -18,13 +18,15 @@
     "patternslib": "https://github.com/Patternslib/Patterns#master"
   },
   "devDependencies": {
+    "@babel/plugin-proposal-optional-chaining": "^7.11.0",
     "@babel/preset-env": "^7.9.6",
     "babel-eslint": "^10.1.0",
     "babel-loader": "^8.1.0",
     "core-js": "3",
     "eslint": "^7.0.0",
-    "jquery": "^3.5.0",
-    "underscore": "^1.9.1",
+    "eslint-config-prettier": "^6.11.0",
+    "prettier": "^2.1.2",
+    "regenerator-runtime": "^0.13.5",
     "webpack": "^4.43.0",
     "webpack-cli": "^3.3.11",
     "webpack-dev-server": "^3.10.3"
@@ -33,31 +35,11 @@
     "start": "webpack-dev-server --config webpack.config.js --open --env.NODE_ENV=development",
     "build": "webpack --config webpack.config.js --env.NODE_ENV=production"
   },
-  "eslintConfig": {
-    "root": true,
-    "env": {
-      "browser": true
-    },
-    "parser": "babel-eslint"
-  },
-  "babel": {
-    "presets": [
-      [
-        "@babel/preset-env",
-        {
-          "useBuiltIns": "entry",
-          "corejs": 3
-        }
-      ]
-    ]
-  },
-  "browserslist": {
-    "production": [
-      ">0.2%",
-      "not dead",
-      "not op_mini all"
-    ]
-  },
+  "browserslist": [
+    ">0.2%",
+    "ie >= 11",
+    "not dead"
+  ],
   "maintainers": [
     {
       "name": "Syslab.com GmbH",