Hi,
I have tried this like below, It is working on my browser but not working on the device.
This file written in lsconnection.js and globally included in my application.
var protocolToUse = document.location.protocol != "file:" ? document.location.protocol : "http:";
var portToUse = document.location.protocol == "https:" ? "443" : "8080";
var lsClient = new Lightstreamer.LightstreamerClient(protocolToUse+"//mydomain.com:"+portToUse,"STOCKLIST_REMOTE");
lsClient.connectionOptions.setHttpExtraHeaders({"u sername" : "bullion"});
lsClient.enableSharing(new Lightstreamer.ConnectionSharing("CommonConnection" , "ATTACH", "CREATE"));
lsClient.connect();

And all of my three controllers written the code like bellow and subscribed in this controller only.
var protocolToUse = document.location.protocol != "file:" ? document.location.protocol : "http:";
var portToUse = document.location.protocol == "https:" ? "443" : "8080";
var lsClient = new Lightstreamer.LightstreamerClient(protocolToUse+"//mydomain.com:"+portToUse,"STOCKLIST_REMOTE");
lsClient.connectionOptions.setHttpExtraHeaders({"u sername" : "bullion"});
lsClient.enableSharing(new Lightstreamer.ConnectionSharing("CommonConnection" , "ATTACH", "CREATE"));
var liverateSubscription = new Lightstreamer.Subscription("COMMAND", liverateId, fieldList);

This working well without terminate the session on browser (ionic serve --lab). But not working after build the app and check in real device.