Help implementing audio dynamic range compression

I am trying to implement audio dynamic range compression in JavaScript (not using web audio API).

There is a lot of articles for sound technicians, and some high level documentation, but I couldn't find any helpful reference for actually implementing digital dynamic range compression.

From what I understand, there is at least 3 steps in calculating the rectified signal.

1. computing the input level


2. computing the gain to apply to the signal


3. applying the gain

I process the audio in blocks, so for 1) I was thinking of computing the RMS of one block

Any pointers to a good reference? Or anybody willing to explain me a bit the steps required to implement this?