A Makefile for bundling javascript

Makefile

all: javascript

javascript: bundle_js min_js

bundle_js: $(patsubst %/,%.bundle.js,$(foreach js,$(sort $(dir $(wildcard src/js/*/*.js))),$(subst src/,static/,$(js))))

min_js: $(patsubst %.js,%.min.js,$(foreach js,$(wildcard src/js/*.js),$(subst src/,static/,$(js))))

static/js/%.min.js: src/js/%.js
        terser $< --safari10 --ecma 5 -c passes=2 -m --mangle-props regex=/^_/ -o $@  

clean:
        rm static/js/*.js 2> /dev/null || true

.PHONY: all clean javascript bundle_js min_js

.SECONDARY:
.SECONDEXPANSION:
static/js/%.bundle.js: $$(sort $$(wildcard src/js/$$*/*.js))
        terser $^ --safari10 --ecma 5 -c passes=2 -m --mangle-props regex=/^_/ \
                -e window,document,location,navigator:window,document,location,navigator \
                -o $@