Why doesn't SKU change with variant selection on my product page?

[Angel_Hernandez]

Greetings

I don't know if this the right place to ask,  but I have a problem that I can't solve. It turns out that in my shirt store I can see the variants but the SKU on the product does not change .. everything else works correctly, the purchase can be made with the correct variant but it does not show the right SKU

selection on the product page

I attach a video

[Prabhat]

This requires a code change to Update the SKU depending upon the variant selected also to handle if there is no SKU available.

Basically, if you can find variant selector js in the theme js it should be straight forward.