Error while subscribing for live data feed in websocket in javascript

[prashant0701_]

Hi @admin and everyone,
I am trying to subscribe to a token using webscoket V2 in javascript. After making a websocket connection I am running following code inside fetchData function:

let req = '{"correlationID":"' + "abcde12345" + '","action":"'+ 1 + '","params":"' + '{"mode":"'+ 1 + '","tokenList":"' + '[{"exchangeType":"' + 1 + '","tokens":"' + '["3045"]'+'"}]}}';

ws.send(req);

I am getting following error:
Error while processing message

Is there anything wrong in the request string?
Please help.

Thanks and regards,
Prashant