deno example by Makefile

lib\foo.js

// lib/foo.js
export default function() {
  console.log('foo.js');
}

lib\hoge\piyo.ts

// lib/hoge/piyo.ts
export default function() {
  console.log('piyo.ts modified');
}

main.js

// main.js
import foo from 'http://localhost:8000/lib/foo.js';
import piyo from 'http://localhost:8000/lib/hoge/piyo.ts';

foo();
piyo();

Makefile

# https://stackoverflow.com/questions/2483182/recursive-wildcards-in-gnu-make
rwildcard=$(foreach d,$(wildcard $(1:=/*)), \
		  $(call rwildcard,$d,$2) \
		  $(filter $(subst *,%,$2),$d))
# http://www.jsk.t.u-tokyo.ac.jp/~k-okada/makefile/
empty:=
space:= $(empty) $(empty)
myjoin=$(subst $(space),$2,$1)
# --------------------------------------------------
LOCAL_ROOT = http://localhost:8000/

MAIN_SRC	= main.js
LIB_SRCS 	= $(call rwildcard,lib,*.js *.ts)

LIB_SRCS	:= $(patsubst %, $(LOCAL_ROOT)%, $(LIB_SRCS))
LIB_SRCS	:= $(strip $(LIB_SRCS))
comma:= ,
LIB_SRCS	:= $(call myjoin,$(LIB_SRCS),$(comma))
# --------------------------------------------------
deno:
	deno run --reload=$(LIB_SRCS) $(MAIN_SRC)

launch local server command example: python -m http.server