How to design Ember JS software?

I am trying to design software which will be written in Ember JS (JavaScript). From research, some people say you can use UML class diagrams, but JavaScript is not a class-based object-oriented language like Java.

Therefore, I am a bit confused with how I should design the Ember JS software. Can anyone recommend a way of designing the software please, or is it okay to use UML class diagrams?

Thank you in advance