Feature Request: Form factor and client browser detection (UserAgent)

[ddaza]

The VCL provides some client helpers for form factor and browser detection. i.e. client.browser.name or client.display.width.

And we would love to use something similar on the JS runtime. The current alternative is to use a collection of regexes on the User Agent, which can slow down the processing of requests.

This would be helpful to us (and others) because we make our experience slightly different for mobile vs desktop as far as loading assets or amount of code.

What are the recommended alternatives to this? And if there is enough buy-in, what would be the timeline of a feature like this?