For what I see 4x no longer has localization. Is there any other method in 4x in front end making $ as default while in backend base currency is euro?
Localization is still supported (though it's somewhat limited, but further along in V4 than prior versions). It allows you to specify language, currency and shipping weights/measures based on country of IP and/or browser settings. You can also specify a localization in a shipping method. However, you can't do anything conditional like profile fields or other things you would expect because those are based on language. I.e. you can't have state for US and not for Ireland because they are both based on 'en' language. However, we have done modifications to address this (as well as localization sensitive images).
[quote name='tbirnseth' timestamp='1422311200' post='203506']
It allows you to specify language, currency and shipping weights/measures based on country of IP and/or browser settings.
[/quote]
How does it work?