praia/examples/websocket_echo.praia at main · praia-lang/praia · GitHub

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#!/usr/bin/env praia
use "socket"

let server = http.createServer(lam{ req in
    if (req.path == "/ws") {
        return socket.upgrade(req, lam{ ws in
            print("[%{ws.id}] connected")

            ws.onMessage(lam{ msg in
                print("[%{ws.id}] received: %{msg}")
                ws.send("echo: %{msg}")
            })

            ws.onClose(lam{ in
                print("[%{ws.id}] disconnected")
            })

            ws.send("Welcome to the echo server!")
        })
    }

    // Serve a simple test page
    return http.html("<!DOCTYPE html><html><body>
<h2>WebSocket Echo Test</h2>
<input id='msg' placeholder='Type a message...' />
<button onclick='send()'>Send</button>
<pre id='log'></pre>
<script>
const ws = new WebSocket('ws://' + location.host + '/ws');
const log = document.getElementById('log');
ws.onopen = () => log.textContent += 'Connected\\n';
ws.onmessage = e => log.textContent += '< ' + e.data + '\\n';
ws.onclose = () => log.textContent += 'Disconnected\\n';
function send() {
    const msg = document.getElementById('msg').value;
    ws.send(msg);
    log.textContent += '> ' + msg + '\\n';
    document.getElementById('msg').value = '';
}
document.getElementById('msg').onkeydown = e => { if (e.key === 'Enter') send(); };
</script></body></html>")
})

print("WebSocket echo server on http://localhost:9090")
server.listen(9090)