This wiki shows how to get the geolocation info of the client using another server API
It could be write also as extension but there are a lots of APIs that change the below code
So, I wrote the below code that works for one of them (using www.geoplugin.net)
The yii2-field-range extension enables you to easily setup ActiveField range fields with Bootstrap styling. You basically can setup two attributes joined together like a single field with combined validation error block.