Add ES module build

Makefile

@@ -3,14 +3,24 @@ SPECFILES := $(shell find $(SPEC_DIR) -iname '*.js')
 SOURCE_DIR := src
 SOURCES := $(shell find $(SOURCE_DIR) -iname '*.js')
 LINTEDFILES := $(SOURCES) $(SPECFILES)
-DISTFILE := build/quantities.js
+BUILD_DIR := build
+ESM_FILE := $(BUILD_DIR)/quantities.esm.js
+UMD_FILE := $(BUILD_DIR)/quantities.js
+DIST_FILES := $(ESM_FILE) $(UMD_FILE)
 BANNER := $(shell cat LICENSE)
 
-build: $(DISTFILE)
+build: $(DIST_FILES)
 
-$(DISTFILE): $(SOURCES)
-	rollup --output.file=$(DISTFILE) \
-         --output.format=umd \
+$(UMD_FILE): $(SOURCES)
+	rollup --file=$(UMD_FILE) \
+         --format=umd \
+         --name=Qty \
+         --banner="`echo '/*'; cat LICENSE; echo '*/'`" \
+         src/quantities.js
+
+$(ESM_FILE): $(SOURCES)
+	rollup --file=$(ESM_FILE) \
+         --format=es \
          --name=Qty \
          --banner="`echo '/*'; cat LICENSE; echo '*/'`" \
          src/quantities.js
@@ -26,6 +36,6 @@ bench:
 	bin/bench.rb
 
 clean:
-	rm -f $(DISTFILE)
+	rm -f $(DIST_FILES)
 
 .PHONY: bench build clean lint test

bin/release.sh

@@ -6,7 +6,7 @@ VERSION=$(cat RELEASE)
 TAG=v${VERSION}
 
 git add History.md README.md bower.json package.json \
-        RELEASE src/quantities.js build/quantities.js
+        RELEASE src/quantities.js build/quantities.js build/quantities.esm.js
 git commit -m "Release ${TAG}"
 git tag "${TAG}"
 git push github master "${TAG}"

package.json

@@ -1,6 +1,7 @@
 {
   "name": "js-quantities",
   "main": "./build/quantities.js",
+  "module": "./build/quantities.esm.js",
   "readmeFilename": "README.md",
   "description": "JavaScript library for quantity calculation and unit conversion",
   "version": "1.7.0",