Upgrade to node 20, eslint 9, flat config, etc

Author: danielnixon

.eslintignore

@@ -15,7 +15,7 @@ jobs:
 
     strategy:
       matrix:
-        node-version: [16.x, 18.x]
+        node-version: [18.x, 20.x]
 
     steps:
     - uses: actions/checkout@3df4ab11eba7bda6032a0b82a6bb43b11571feac # v4

.eslintrc.js

@@ -102,3 +102,6 @@ dist
 
 # TernJS port file
 .tern-port
+
+# OS junk
+.DS_Store

.github/workflows/node.js.yml

@@ -1 +1 @@
-18
+20

.gitignore

@@ -11,16 +11,15 @@ Agile Digital's standard ESLint config
 
 ```sh
 yarn add --dev @agiledigital/eslint-config \
-  eslint-config-typed-fp \
-  @typescript-eslint/eslint-plugin \
-  @typescript-eslint/parser \
+  @eslint/compat \
+  @eslint/eslintrc \
+  typescript-eslint \
   eslint \
   eslint-plugin-functional \
-  eslint-plugin-total-functions \
   eslint-plugin-jest \
   eslint-plugin-prettier \
   eslint-plugin-sonarjs \
-  eslint-plugin-import \
+  eslint-plugin-import-x \
   eslint-plugin-simple-import-sort \
   eslint-plugin-filename-rules \
   eslint-plugin-jsdoc \

.nvmrc

@@ -0,0 +1,12 @@
+// FIXME why is this rule triggered here?
+// eslint-disable-next-line import-x/no-unresolved
+import tseslint from "typescript-eslint";
+import base from "./index.mjs";
+import react from "./react.mjs";
+// This lint config is used for test the combination of base and react config.
+// It only extends settings from base and react eslint config.
+// eslint-disable-next-line functional/prefer-immutable-types
+const config = tseslint.config({
+    extends: [...base, ...react],
+});
+export default config;

README.md

@@ -0,0 +1,15 @@
+// FIXME why is this rule triggered here?
+// eslint-disable-next-line import-x/no-unresolved
+import tseslint from "typescript-eslint";
+import base from "./index.mjs";
+import react from "./react.mjs";
+
+// This lint config is used for test the combination of base and react config.
+// It only extends settings from base and react eslint config.
+
+// eslint-disable-next-line functional/prefer-immutable-types
+const config = tseslint.config({
+  extends: [...base, ...react],
+});
+
+export default config;