Code coverage for js based electronic application

I have a js based e-app which I have automated with selenium webdriver and testng. In a script, I am using chrome driver exe to open an electronic app and automate test cases. Now I want to generate a code coverage report using my automation test suite written in java with selenium webdriver. How can I achieve the same, is there any tool or link that can help me get code coverage for an electronic application.

I am currently using istanbul to get coverage code for websites developed with node js.

Thanks in advance!