How to approach TDD approach in frontend development

As we know, TDD stands for "write the test first, and then write the code".

However, when it comes to UI development, writing unit tests first is a bit tricky (to me) Not sure how to proceed. As we know unit tests validate the behaviour of function, not a state. How can I validate the template first? I was asked in the same fashion in one of my interviews that how will you follow the TDD approach in frontend development. Thoughts?