From ea3adcfc93fed6d7060b514599d7ff3e4bd1ab6f Mon Sep 17 00:00:00 2001
From: Trevor Manz <trevor.j.manz@gmail.com>
Date: Sun, 14 Mar 2021 06:04:30 -0400
Subject: [PATCH] Add package.json `exports` field (#773)

These changes adds an `exports` field to package.json with the main
goal of allowing the root/main export to be our ESM syntax version of
the package, as opposed to the UMD/CommonJS version.

This will make it easier for using projects written with ESM to use
mustache.js out of the box, without having to figure out that they'd
have to `import mustache/mustache.mjs` to get the ESM version.

It is also assumed to be beneficial for tools like http://skypack.dev
to choose the correct ESM version when appropriate.

Refs https://nodejs.org/api/packages.html#packages_package_entry_points
---
 .github/workflows/usage.yml              |  2 ++
 package.json                             |  7 +++++++
 test/module-systems/esm-test-exports.mjs | 12 ++++++++++++
 3 files changed, 21 insertions(+)
 create mode 100644 test/module-systems/esm-test-exports.mjs

diff --git a/.github/workflows/usage.yml b/.github/workflows/usage.yml
index 75d68ff..f22ede8 100644
--- a/.github/workflows/usage.yml
+++ b/.github/workflows/usage.yml
@@ -90,9 +90,11 @@ 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
diff --git a/package.json b/package.json
index f5dda06..bec0f76 100644
--- a/package.json
+++ b/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"
   },
diff --git a/test/module-systems/esm-test-exports.mjs b/test/module-systems/esm-test-exports.mjs
new file mode 100644
index 0000000..d79feb6
--- /dev/null
+++ b/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'
+);