['1', '2', '3'].map(parseInt);
// While one could expect [1, 2, 3]
// The actual result is [1, NaN, NaN]
parseInt is often used with one argument, but takes two.
The first is an expression and the second is the radix.
To the callback function, Array.prototype.map passes 3 arguments: the element, the index, the array.
The third argument is ignored by parseInt, but not the second one, hence the possible confusion.
['1', '2', '3'].map(parseInt); // While one could expect [1, 2, 3] // The actual result is [1, NaN, NaN]
parseInt is often used with one argument, but takes two. The first is an expression and the second is the radix. To the callback function, Array.prototype.map passes 3 arguments: the element, the index, the array. The third argument is ignored by parseInt, but not the second one, hence the possible confusion.