Hello,
I would have Pd talk to whatever's hosting your webpage using OSC.
I wrote a piece a few years ago that had SuperCollider (but I later ported it to Pd) talking to a webpage I hosted on my computer via node.js via OSC (I think I used the 'node-osc' library in particular). So Pd talks to node via OSC and then node calls js functions in your webpage's js files.
Then I targeted individual clients who connected to my page via soc ket.io so I could pick out invidiual cell phones to trigger sounds on (but this bit isn't necessary for the Pd -> webpage communication...)
I have the boilerplate from that piece abstracted out here: https://github.com/derekxkwan/socketMusicBoiler . Haven't looked at that repo basically since 2015 so not sure of the quality of the documentation...
Derek
www.derekxkwan.com