I'm a true believer that tests are a crucial part of software development, but I realise that it can be quite hard to learn how to test frontend apps.
I've looked before for resources on how to learn frontend testing (to share with people) but apart from very long video courses, there were not too many good resources.
So I thought I would build it the way I wish I had it, when I learned frontend testing!
I've split the site up into 'courses'. Some are free, some are paid. Almost all include an interactive test runner to run tests in your browser. (The only exceptions are lessons where simulating Vitest/Jest in the browser is hard or not possible.)
Any questions or feedback? Please reach out. I'm also very open to hearing about what confuses you about frontend testing - and I'll try to get something to cover it on the site. You can also reach out on Twitter @howToTestFE.