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
janl · Mar 14, 2021 · ea3adcf · ea3adcf
1 parent f15befd
commit ea3adcf
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diff --git 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
@@ -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
@@ -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'
+);