I am working on an international site that requires the user to enter his postal address. I am wondering if it makes sense to have a slightly different order of input fields in favor of a time saving pre-fill feature.
This is the common format for US address input fields:
I am thinking of something that goes like this:
Let's assume it would be possible to detect the City and State correctly after the user entered the ZIP code (I am aware of some ZIPs not being unique in the US). Once the user left the ZIP code input field (onMouseOut) I'd like pre-fill the other two fields.
My question is: Would it really harm the user experience if I changed the input field order, i.e. would many users stumble or even drop off?