Question

I’m just wondering what it means to attach a number as a parameter to the toString() method

E.g. obj.toString(10);

I googled and i have never seen a parameter before.

Answer 1

The additional parameter works only for Number.prototype.toString to specify the radix (integer between 2 and 36 specifying the base to use for representing numeric values):

var number = 12345;
number.toString(2) === "11000000111001"
number.toString(3) === "121221020"
// …
number.toString(36) === "9ix"