var WebSocketServer = require('ws').Server,
wss = new WebSocketServer({ port: 8080 });
wss.on('connection', function (ws) {
console.log('client connected');
ws.on('message', function (message) {
 console.log(message);
});
});

<script>
var ws = new WebSocket("ws://localhost:8080");
ws.onopen = function (e) {
 console.log('Connection to server opened');
 sendMessage();
}
function sendMessage() {
 ws.send('hello');
}
</script>