This is exactly backwards. One needs to start with the needs of the user, which means mocking up the user experience without regard for implementation. The tool

This is exactly backwards. One needs to start with the needs of the user, which means mocking up the user experience without regard for implementation. The tool might vary, but the concept of starting with the user is essential. Starting in code makes it about the coder, not the user. It conflates implementation with design. I am a coder, and will do mockups in code -- only when I know a real design won't be available. I would much rather be directed by a good UX person. Better for the user, and faster for me as an implementor.