Provide a way to progressively enhance an input

[edwardhorsford]

The autocomplete needs to be able to progressively enhance from an input as well as a select.

Where the options are known and reasonably few in number (countries), select is fine. For a large number of options or unknown options, we need an input. Non js would submit what the user enters - the server can then do their own checks, or search or whatever.

Related to #95. Also the opposite of #198

[trevorkapswarah]

Hi,

This is an issue we have faced too as we need an existing input element to be bound to the autocomplete functionality as the input element can serve more than one purpose.

https://github.com/alphagov/govuk-design-system-backlog/issues/4#issuecomment-457176135

[matthewford]

We're using it to enhance an input on the trade tariff's search: https://www.trade-tariff.service.gov.uk/sections?currency=EUR