Too Long; Didn't Read
Facebook's Jest and Mocha are two of the most popular JavaScript testing tools for Javascript. Jest is particularly popular for testing React and is well integrated with other React testing tools such as Enzyme. Mocha's test runner, however, comes without a built-in assertion library, and instead integrates other complementary packages to provide a complete experience. The choice of one framework over another really depends on the specific needs for the project, as well as a pinch of personal preference of course.