Can't get native messaging to work in Chrome Extension - windows

Question

Hope you can help me. I need to call an executable jar from an Chrome-Extension. By research I found https://developer.chrome.com/extensions/messaging#native-messaging is the way to go.
So I first edited the manifest of my extension and added:
"permissions": [
"nativeMessaging"
],
I can see in the Extensions overview, that the permission is granted.
As I am operating on Windows I added a Registry-Key:
HKEY_LOCAL_MACHINE\SOFTWARE\Google\Chrome\NativeMessagingHosts\myextension
with:
C:\path\to\myextension.json
the "myextension.json" contains:
{
"name": "myextension",
"description": "my extension",
"path": "myextension.bat",
"type": "stdio",
"allowed_origins": [
"chrome-extension://[key]/"
]
}
the myextension.bat contains:
#echo off
cd %windir%\system32
start calc.exe
(for testing just wanted to start the calculator)
in the js of my extension I try to call it by this:
var port = null;
var hostName = "myextension";
[...]
$(this).children(".abc").click(function() {
//alert("test");
port = chrome.runtime.connectNative(hostName);
alert(port);
message = {"text": "nachricht"};
port.postMessage(message);
});
But nothing happens. The first alert "test" would be executed. But other than that nothing happens.
I really don't know how to debug it, because I don't get any feedback by executing it. Hope you can help me.
/edit
Just saw that I get:
"Uncaught TypeError: undefined is not a function (anonymous function)"
at:
port = chrome.extension.connectNative(hostName);
or
port = chrome.runtime.connectNative(hostName);
/edit 2
Ok, now I got it to work when I use a button in the browser with: chrome.browserAction.onClicked.addListener(function() {
chrome.extension.connectNative('fbehost');
});
But when I want to call it from a button in the website it doesn't work:
$(this).children(".abc").click(function() {
alert("Test");
port = chrome.extension.connectNative("fbehost");
});
The alert works, but nothing else happens.