I found some strange behavior in the javascript parse int function.
Check the following code:
console.log([..."111"].map(Number.parseInt))
console.log([..."111"].map(x => Number.parseInt(x)))When you run the first line, you get: [1, Nan, 1]
When you run the second line, you get: [1, 1, 1]
Can someone explain this strange behavior?
The parseInt() function is defined with two parameters: the string to parse, and a number indicating the numeric base to assume for the string representation. On the second iteration, the .map() call is effectively calling
Number.parseInt("1", 1)
and base 1 does not make sense. (Base 0 does not make sense either, but it ignores that.)
Recall that the .map() function passes 3 parameters to its callback function: an element from the array, an index, and the array itself.
Number.parseInt accepts 2 arguments if the second argument (called radix in MDN docs) is smaller than 2 or greater than 36, NaN is returned.