Only the James' is technically correct
@Parker 又 I feel like that’s what I do too!! My son’s name ends in an S & it’s what I do with him
@Annie Merriam-Webster says both are correct options! 
James’. Really annoys me when people do s’s 😂
'S is short for "is" "James's toys" is actually "James is toys" Names ending in s should only have ' at the end "These are James' toys"
I think both are accepted but I prefer the first. I like the consistency of adding ‘s for singular possession. The second one just looks off/ hits the ear wrong for me.
@Tara I think shortening applies in some cases - Let us go to the shops/ Let’s go to the shops - but not with this?
We learned in school it should be James’ pronounced James not James’s because that would be pronounced Jameses which isn’t correct grammar.
'S for names, but just an ' for nouns x
If I was writing it I’d probably do just the apostrophe but I know when I speak verbally I say it more like the apostrophe & the s lmfao