How does WEBRTC works? Is it possible to implement a demo offline?

How does WEBRTC works? Is it possible to implement a demo offline?
Which I need is:
Open two windows on browser, without web server, and send messages between them.
For example:

    const localPeer = new RTCPeerConnection();
    const offer = localPeer.createOffer();
    localPeer.setLocalDescription(offer)
    // output offer as TEXT on page
    const remotePeer = new RTCPeerConnection();
    remotePeer.setRemoteDescription(/* input the TEXT offer here*/);
    const answer = await remotePeer.createAnswer()
    remotePeer.setLocalDescription(answer)
    // output answer on page as TEXT
    localPeer.setRemoteDescription(/* input the TEXT answer here */)
    const localChannel = localPeer.createDataChannel("test")
    const remoteChannel = remotePeer.createDataChannel("test")
    localChannel.addEventListener("message", () => {})
    remoteChannel.addEventListener("message", () => {})

is it possible?

here is the demo, and it seems doesn’t work.
https://github.com/flowfire/demo-webrtc-001