Nested makefile and libraries from CDN

Makefile

@@ -1,37 +1,31 @@
 
-JS_SOURCES = $(wildcard frontend/src/*.js)
-JS_OUTPUTS = $(patsubst frontend/src/%.js, public/js/%.min.js, $(JS_SOURCES))
-SERVER_EXECUTABLE = phc-website-server
+GO_SOURCES = $(shell find . -name '*.go')
+GO_EXECUTABLE = phc-website-server
 
 .PHONY: all
 all: js go
 
-#
-# Build Frontend
-#
+.PHONY: setup
+setup:
+	mkdir -p public/js
 
 .PHONY: js
-js: $(JS_OUTPUTS)
-	@echo "Compiled Frontend"
-
-public/js/%.min.js: frontend/src/%.js
-	cd frontend; rollup -c rollup.config.js
-	mkdir -p public/js
-	cp $(patsubst frontend/src/%.js, frontend/dist/%.min.js, $<) $@
+js: setup
+	$(MAKE) -C frontend/
+	cp frontend/dist/*.min.js public/js/
 
 #
 # Build Server
 #
 
 .PHONY: go
-go: $(SERVER_EXECUTABLE)
+go: $(GO_EXECUTABLE)
 	@echo "Compiled Server"
 
-$(SERVER_EXECUTABLE):
-	go build -o $(SERVER_EXECUTABLE) .
+$(GO_EXECUTABLE): $(GO_SOURCES)
+	go build -o $(GO_EXECUTABLE) .
 
 .PHONY: debug
 debug:
-	@echo "JS_SOURCES = $(JS_SOURCES)"
-	@echo "JS_OUTPUTS = $(JS_OUTPUTS)"
-	@echo "SERVER_EXECUTABLE = $(SERVER_EXECUTABLE)"
+	@echo "GO_SOURCES = $(GO_SOURCES)"
+	@echo "GO_EXECUTABLE = $(GO_EXECUTABLE)"