[JS] Use console.group for debugging

Grouping Log Messages Using console.group()

You can group related log statements by surrounding them with the console.group()and console.groupEnd() functions:

console.group("URL Details");
console.log("Scheme: HTTPS")
console.log("Host: example.com");
console.groupEnd();

refer to:
http://www.jquerybyexample.net/2015/01/javascript-logging-using-console-group.html
https://developer.chrome.com/devtools/docs/console-api
https://developer.mozilla.org/en-US/docs/Web/API/Console