Why does changing one array alters the other?

Question

Consider this tiny bit of javascript code:

var a = [1, 2, 3],
    b = a;

b[1] = 3;

a; // a === [1, 3, 3] wtf!?

Why does \"a\" change when

Answer 1

All Javascript objects are passed by reference - you would need to copy the entire object, not assign it.

For arrays this would be simple - just do something like:

var a = [1, 2, 3];
var b = a.slice(0);

where slice(0) returns the array from offset 0 to the end of the array.

This link has more info.