I'm not properly answering the question but, I think it makes sense to clear why we should specify the radix.
On MDN documentation we can read that:
If radix is undefined or 0 (or absent), JavaScript assumes the following:
- [...]
- If the input string begins with "0", radix is eight (octal) or 10 (decimal). Exactly which radix is chosen is implementation-dependent. ECMAScript 5 specifies that 10 (decimal) is used, but not all browsers support this yet. For this reason always specify a radix when using parseInt.
- [...]
Source: MDN parseInt()