Why does parseInt yield NaN with Array#map?

Question

From the Mozilla Developer Network:

[1,4,9].map(Math.sqrt)

will yield:

[1,2,3]

Why then does this:

<

Answer 1

another (working) quick fix :

var parseInt10 = function(x){return parseInt(x, 10);}

['0', '1', '2', '10', '15', '57'].map(parseInt10);
//[0, 1, 2, 10, 15, 57]