Look at the following Logo of Jest, a testing framework by Facebook.
And indeed, Facebook have an excellent reason to use this slogan. In general, JS developers are not too happy with website testing. JS tests tend to be limited, hard to implement, and slow.
Nevertheless, with the right strategy and the right combination of tools a nearly full coverage can be achieved and tests can be very organized, simple, and relatively fast.
... read the whole story at medium.com.