Until recently I mostly used the Mocha / Chai / Istanbul tool chain in order to test Javascript / Typescript. However that had some downsides it had a lot of set up, lacked a good mocking library and didn't integrate in to Angular for testing. I therefore have switched over to use Jest for testing new projects.

I have set up jest in new projects , and written by this point many 1000s of tests in jest making use of jest matchers and jests in build mocking framework. This is both in vanilla frontend JS, node , and Angular.