data/websocket/connect_to.html

<!DOCTYPE html>
<html>
<head>
<title>test ws connection</title>
<script type="text/javascript">

var href = window.location.href;
var queryBegin = href.indexOf('?url=');
if (queryBegin == -1) {
  console.log("Failed to find ?url= in URL");
  document.title = 'FAIL';
  throw "FAILURE";
}
var url = href.slice(queryBegin + 5);

// Do connection test.
var ws = new WebSocket(url);

ws.onopen = function()
{
  // Set document title to 'PASS'. The test observer catches this title changes
  // to know the result.
  document.title = 'PASS';
}

ws.onclose = function()
{
  // Set document title to 'FAIL'.
  document.title = 'FAIL';
}

ws.onmessage = function(evt)
{
  domAutomationController.send(evt.data);
}

ws.onerror = function(evt)
{
  console.error(`WebSocket error: '${JSON.stringify(evt, ["message", "arguments", "type", "name"])}'`);
}

</script>
</head>
</html>