.PHONY 用来告诉 make 和文件无关的命令。
PS：经我测试不加也行。。我用的版本：
bash
$ make -v
GNU Make 4.3
Built for Windows32
测试代码：
makefile
# .PHONY: build build-bundle clean test-clean lint lint-js lint-ts
build: build-bundle
echo build
build-bundle: clean
echo build-bundle
clean: test-clean
echo clean
test-clean:
echo test-clean
lint: lint-js lint-ts
echo lint
lint-js:
echo lint-js
lint-ts:
echo lint-ts
See: What is the purpose of .PHONY in a Makefile? - Stack Overflow