Custom Fields: String with Cart Attribute

[marvays]

Hi all.
I have Custom Field Type: String.
In produst i have 3 variant: 50w; 60w and 80w
Layout position: addtocart
Cart Attribute and Cart Input set yes

All work nice. But if i try st in "Additional Parameters" -> "as radiolist" to "Yes" i havent select first of parameter. Can i solve this problem to auto select first param after page load?

I have joomla 3.6.3
VM 3.0.18

THX

[kishoreonwork]

Yes ,I believe it is possible with simple JavaScript code. Please provide me a link to the product detail page to provide exact code for it .

Thanks
Kishore

[marvays]

Thank you for your response. I found the extension of the third party that settles it. once again thank you for your interest.