I'm there in JavaScript for a long time & it still gives me new things to learn.
According to me, the following line should print the same array back, perhaps it doesn't -
console.log([2, 2, 2, 2, 2, 2].map(parseInt));
// output => [2, NaN, NaN, 2, 2, 2]
console.log([2, 2, 2, 2, 2, 2].map((num) => parseInt(num)));
// output => [2, 2, 2, 2, 2, 2]Could anyone please help me understand this?
yes so what are the arguments to callback of map
value,index,array
your code sample is executed like this:
console.log(
[2, 2, 2, 2, 2, 2].map((value, index) => {
return parseInt(value, index);
})
);so you are passing second argument to parseInt , which is index
2nd argument to parseInt is base in which you want to parse the integer
for base 1 and 2 there is no digit 2 .. so it gives NaN
read more about 2nd parameter of parseInt on MDN
Fix is providing only one argument since your numbers are in base 10
console.log(
[2, 2, 2, 2, 2, 2].map(value => parseInt(value))
);
