Good point. I've edited my comment to be more qualified.
The web is a fascinating study of advice that changed over time: there’s something like a half-decade window where the two argument form became common, with unsafe usage before and safe usage after.
In most browser implementations (at least all the ones we develop for) it would assume a radix of 10 for those values specifically.
this is a relic from issues in ie8, and you no longer need to do this if you're not supporting ie8. hell even if you use ie8 in almost 99% of cases you won't need to bother.