so I am trying to use javascript or python (or anything else that can do it) to get the pitch and volume of an mp3 file at every few milliseconds. Any help would be greatly appreciated, thank you.
Pitch is related to how fast the amplitude of a signal changes, so it needs to be calculated over a block of time, rather than at an instant.
I'd suggest decoding your mp3 into a waveform (there are Python libraries that will put this in a numpy array for you) then take a section at a time and do the following:

Run an FFT (search for numpy FFT) on the block to find the frequency content. Typically a sound at a particular pitch will have a base frequency and there will also be harmonic content i.e. frequencies at integer multiples of the base frequency. Additionally, you may have more than one contributing sound, so there will be multiple base frequencies each with their own harmonics. The FFT will work out what frequencies there are assuming that he block then repeats forever. Unfortunately the start and end amplitude of your signal won't match at the start and end of your block, so this assumption is like there's a sudden jump in amplitude. That is going to cause artifacts in your FFT result, so if it is a problem in your application you will need to look into windowing before running an FFT. This attenuates your block at the start and end, so they line up at zero.
Identify which FFT peak relates to the pitch you want to record. This may be the highest peak for example. The frequency of this peak is the pitch for this block.
Take the root-mean-squared (RMS) of the block (from the original array, not the FFT) and use this as a measure of volume.

You can then move to the next block and repeat, so if your block size is 440 samples (10ms at 44kHz sampling rate) take your first block from 0 to 439, then the next from 440 to 879 etc.
You could also do a sliding block if you want, e.g. advance your 440 sample block by say 44 samples each time, so the first block is 0 to 439 and the next is 44 to 483.
Get pitch of mp3 files at every few ms