parseInt turns 10.937 into 10, 0.2 into 0, and “someValue” into
NaN. If you use
parseInt without a radix, however, you’ll receive a warning that no radix has been provided. In most cases, the radix you want to use is 10:
parseInt(10.83, 10); // 10, no warning
parseInt(.83, 10); // 0, no warning
parseInt(0.8); // 8, unintended result
parseInt(0.8, 10); // 0, intended result
Using a 10 radix means the number is parsed with a base 10 and thus turns the number into the integer you’re expecting, without the annoying warning. The radix is important if you’re need to guarantee accuracy with variable input (basic number, binary, etc.).
For best results, always use a radix of 10!