JSCover

JSCover is a lightweight, yet handy application designed to instrument the JavaScript code in web pages. It collects code coverage statistics and measures line and branch coverage using a web browser.

The idea behind the tool is to add the instrumentation to the JavaScript before it is executed in a web page using three different methods. By far the simplest one entails employing the server mode, which has the role of instrumenting the JavaScript as it is served by a simple web server.The server can be run with a proxy option, which in turn makes the server a proxy server capable of instrumenting the code that passed through the connection. Lastly, the tool enables the use of a file-system mode program to generate instrumented JavaScript files.

As far as the measured features are concerned, you can count several critical ones, including, but not limited to coverage measured directly through the browser that allows DOM interaction, ES6/7/8 support as per the closure-compiler or Run JavaScript tests and running JavaScript tests and collect coverage in a single Java test class with WebDriver, just to name a few.

It is worth mentioning that all reports are available in various formats, namely XML summary, Cobertura XML and LCOV.