much stricter eslint'ing (adapted from eslint-config-google and some airbnb)

.eslintrc.json

@@ -12,7 +12,7 @@
   ],
   "parser": "@babel/eslint-parser",
   "parserOptions": {
-    "ecmaVersion": 2015,
+    "ecmaVersion": 2018,
     "sourceType": "module",
     "allowImportExportEverywhere": false,
     "requireConfigFile": false,
@@ -24,14 +24,95 @@
       ]
     }
   },
-  "rules": {
-    "curly": "error",
-    "quotes": ["error", "double"]
-  },
   "env": {
     "browser": true,
     "es6": true
   },
+  "rules": {
+    // Stylistic:
+    "brace-style": "error",
+    "camelcase": ["error", {
+      "properties": "never",
+      "ignoreDestructuring": true
+    }],
+    "comma-dangle": ["error", "always-multiline"],
+    "comma-spacing": "error",
+    "comma-style": "error",
+    "curly": ["error", "multi-or-nest", "consistent"],
+    "func-call-spacing": "error",
+    // "indent": ["error", 2, {
+    //   "ignoredNodes": ["JSXElement", "JSXElement > *", "JSXAttribute", "JSXIdentifier", "JSXNamespacedName", "JSXMemberExpression", "JSXSpreadAttribute", "JSXExpressionContainer", "JSXOpeningElement", "JSXClosingElement", "JSXFragment", "JSXOpeningFragment", "JSXClosingFragment", "JSXText", "JSXEmptyExpression", "JSXSpreadChild"]
+    // }],
+    "max-len": ["error", {
+      "code": 100,
+      "tabWidth": 2,
+      "ignoreUrls": true,
+      "ignoreComments": false,
+      "ignoreStrings": true,
+      "ignoreRegExpLiterals": true,
+      "ignoreTemplateLiterals": true
+    }],
+    "no-multiple-empty-lines": ["error", { "max": 1 }],
+    "no-tabs": "error",
+    "no-trailing-spaces": "error",
+    "object-curly-spacing": ["error", "always"],
+    "one-var": ["error", {
+      "var": "never",
+      "let": "never",
+      "const": "never"
+    }],
+    "operator-linebreak": ["error", "after"],
+    "padded-blocks": ["error", "never"],
+    "quote-props": ["error", "consistent"],
+    "quotes": ["error", "double", {
+      "avoidEscape": true,
+      "allowTemplateLiterals": true
+    }],
+    "semi": "error",
+    "semi-spacing": "error",
+    "space-before-blocks": "error",
+    "space-before-function-paren": ["error", {
+      "named": "never",
+      "anonymous": "always",
+      "asyncArrow": "always"
+    }],
+    "spaced-comment": ["error", "always", {
+      "line": {
+        "markers": ["/"],
+        "exceptions": ["-", "+"]
+      },
+      "block": {
+        "markers": ["!"],
+        "exceptions": ["*"],
+        "balanced": true
+      }
+    }],
+    "template-tag-spacing": ["error", "never"],
+
+    // ES6:
+    "arrow-body-style": ["error", "as-needed", { "requireReturnForObjectLiteral": false }],
+    "arrow-parens": ["error", "always"],
+    "arrow-spacing": ["error", { "before": true, "after": true }],
+    "no-confusing-arrow": ["error", { "allowParens": true }],
+    "no-var": "error",
+    "prefer-const": ["error", {
+      "destructuring": "any",
+      "ignoreReadBeforeAssign": true
+    }],
+    "prefer-destructuring": ["error", {
+      "VariableDeclarator": {
+        "array": false,
+        "object": true
+      },
+      "AssignmentExpression": {
+        "array": true,
+        "object": false
+      }
+    }],
+    "prefer-rest-params": "error",
+    "prefer-spread": "error",
+    "template-curly-spacing": "error"
+  },
   "overrides": [{
     "files": [
       "api/**/*.ts"
@@ -50,8 +131,6 @@
     ],
     "parser": "@typescript-eslint/parser",
     "parserOptions": {
-      "ecmaVersion": 2020,
-      "sourceType": "module",
       "project": ["./tsconfig.json"]
     },
     "rules": {
@@ -59,9 +138,14 @@
     },
     "env": {
       "browser": false,
-      "node": true,
-      "es6": true
+      "node": true
     }
   }],
-  "ignorePatterns": ["public/**", "static/assets/**", "postcss.config.js", "gulpfile.js", "webpack.config.js"]
+  "ignorePatterns": [
+    "public/**",
+    "static/assets/**",
+    "*.d.ts",
+    "gulpfile.js",
+    "webpack.config.js"
+  ]
 }