Maintenance: build, esm, dependency and linting (#84)

This is major maintenance commit that improves the build process.
It does not change the functionality of the library.

* Use file extensions in imports. Extensionless imports are not supported in esm.
  This required adding .js in all import statements
* Provide esm module along with commonjs module
* Base the demo on the esm module
* Upgrade eslint to 9.0.0. json based config file is now deprecated.
  Migrate to eslint.config.js
* Above changes also should fix the broken build process in the CI
  Build it in more recent node versions too.
* Bump version to 2.4.0

.github/workflows/node.js.yml

@@ -16,7 +16,7 @@ jobs:
 
     strategy:
       matrix:
-        node-version: [12.x, 14.x, 16.x, 18.x]
+        node-version: [18.x, 20.x, 22.x]
         # See supported Node.js release schedule at https://nodejs.org/en/about/releases/
 
     steps:

demo/index.html

@@ -6,8 +6,7 @@
 		<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
 		<title>Banana i18n Demo</title>
 		<meta name="author" content="Santhosh Thottingal">
-		<script src="../dist/banana-i18n.js"></script>
-		<script src="js/demo.js"></script>
+		<script src="js/demo.js" type="module"></script>
 		<link rel="stylesheet" type="text/css" href="css/style.css" />
 	</head>
 

demo/js/demo.js

@@ -1,3 +1,5 @@
+import Banana from '../../dist/esm/banana-i18n.js'
+
 const banana = new Banana()
 
 function updateText () {

eslint.config.js

@@ -0,0 +1,21 @@
+import globals from "globals";
+import pluginJs from "@eslint/js";
+import tseslint from "typescript-eslint";
+
+export default [
+  {
+    files: ["**/*.{js,mjs,cjs,ts}"],
+    ignores: ["dist/**/*"],
+  },
+  {
+    languageOptions: {
+      globals: {
+        ...globals.browser,
+        ...globals.node,
+        ...globals.mocha
+      }
+    }
+  },
+  pluginJs.configs.recommended,
+  ...tseslint.configs.recommended,
+];