What is a good test coverage percent for Javascript code?

I am working on a project with a very important front-end part. It is made with Javscript using JQuery for lots of things. We have also included some tests with Mocha. I don't know what rules (percentage) should be reasonable for code coverage in our tests.

As it has a lot of interactions with the DOM, and that cannot be unit tested, I just see impossible to achieve the highly recommended 80%. Not event a 50%. Is there any guidelines on what testing ratios are good for UI code?