2 of 2 people found this helpful
Yep, definitely no reason for a back-end API to be used for this function (and it would be very complex to build that way due to timing issues). It can be built easily using the Forms JS API.
You're right that the built-in AutoFill from cookie only works w/fields of the Hidden type.
But you can make AutoFill work with regular, visible fields too. Exactly like this: MktoForms2 :: AutoFill from cookie
Just download and include the FormsPlus utility script (in the HTML pane) and follow the concept in the JS pane.