JavaScript API to serial port?

Is there a JavaScript API to the serial port when using Arduino Create? I know that Arduino Create uses SPJS and web sockets to get access to serial ports. On my website, I'd like to interface with the serial data being output by my own Arduino programs and plot that data, or cause certain events to happen, etc. I imagine for security reasons, a web socket can only be established from Arduino's domain, but I was wondering if there's any sort of iframe messaging interface (or way to allow my own domain access to SPJS).

I found a config file that allows me to add my own domain to the allow origins list: ~/Applications/ArduinoCreateAgent/

I think this will be sufficient!

Indeed it's for security reason that access is allowed only from arduino domains, The messaging interface is not well documented, but basically you can send a list message to obtain a list of the connected boards, an open message to start reading from a port.