Javascript variable with leading zeroes

Question

Javascript behaves differently with values having leading zeroes. alert(b) - prints different value.

var a = 67116;
var b = 00015;
alert(a);
alert(b);

I am more interested to know What conversion is applied here by javascript inside alert(b) ? (If i have them in double quotes. They work fine.)

Answer 1

var b = 00015

is an octal number

see this question for solution