Add package.json exports field

.github/workflows/usage.yml

@@ -64,9 +64,11 @@ jobs:
           export UNPACK_DESTINATION=$(mktemp -d)
           mv mustache.tgz $UNPACK_DESTINATION
           cp test/module-systems/esm-test.mjs $UNPACK_DESTINATION
+          cp test/module-systems/esm-test-exports.mjs $UNPACK_DESTINATION
           cd $UNPACK_DESTINATION
           npm install mustache.tgz
           node esm-test.mjs
+          node esm-test-exports.mjs
 
   browser-usage:
     runs-on: ubuntu-latest

package.json

@@ -24,6 +24,13 @@
     "mustache.min.js",
     "wrappers/"
   ],
+  "exports": {
+    ".": {
+      "import": "./mustache.mjs",
+      "require": "./mustache.js"
+    },
+    "./*": "./*"
+  },
   "volo": {
     "url": "https://raw.github.com/janl/mustache.js/{version}/mustache.js"
   },

test/module-systems/esm-test-exports.mjs

@@ -0,0 +1,12 @@
+import assert from 'assert';
+import mustache from 'mustache';
+
+const view = {
+  title: 'Joe',
+  calc: () => 2 + 4
+};
+
+assert.strictEqual(
+  mustache.render('{{title}} spends {{calc}}', view),
+  'Joe spends 6'
+);