Hello world from Static HTML file
<script>
    const wsUrl = new URL(`/api/ws?id=123`, location)
    wsUrl.protocol = 'wss:'

    const ws = new WebSocket(wsUrl)
    ws.onerror = e => console.log('[ws] error:', e)

    var siId
    ws.onopen = () => {
        console.log('[ws] opened')
        siId = setInterval(() => {
            ws.send('Hello from client: ' + (new Date).toLocaleString())
        }, 1000)
    }
    ws.onclose = () => {
        console.log('[ws] closed')
        if (siId) {
            clearInterval(siId)
            siId = undefined
        }
    }
    ws.onmessage = e => console.log('[ws]:', e.data, ', client date:', (new Date).toLocaleString())
</script>