Build a script to merge two .env files usung typescript

I want to write a function in typescript to merge to .env files but override some values like shown below
=> .env File 1
API_HOST=testData1
#comment one
API_KEY=testdata2
FOO=bar

=> env File 2
X_API_HOST=testData3
X_API_HOST=testData4
# Comment two
FOO=baz

Final env
API_HOST=testData1
#comment one
API_KEY=testData2
X_API_HOST=testData3
X_API_HOST=testData4
# Comment two
FOO=baz