AI solution for JavaScript Quiz on BFE.dev
16. parseInt

The code below outputs the following by console.log:

[0]
[0, NaN]
[0, 1, NaN]
[0, 1, 1, NaN]

This unexpected output is because the .map() method passes in three arguments to the callback function, and parseInt() uses the second argument as the radix (or base) for the conversion. Therefore, the values in the first column (['0', '1', '1', '1']) are being converted to integers using different radices when passed into parseInt(). Here's a breakdown of the conversion that occurs in each iteration:

• parseInt('0', 0) returns 0
• parseInt('1', 1) returns NaN because there is no digit 1 in base 1
• parseInt('1', 2) returns 1 in base 2
• parseInt('1', 3) returns 1 in base 3

To avoid this confusion, it's recommended to use the unary plus operator (+) instead of parseInt() to convert strings to numbers.