Question

Possible Duplicate:
Workarounds for JavaScript parseInt octal bug

Surprisingly it returns 0. Why? and what’s the (proper) solution to get correct results?

Answer 1

Use a radix:

var x = parseInt("08", 10);

Some JavaScript implementations add a third numeral system to the two defined by the standard (decimal, the default; and hex, prefixed with 0x): Octal, prefixed with 0. This is non-standard but acknowledged as common in the latest spec.

Since 8 is not a valid octal digit, parseInt stops there, returning the value 0.

By explicitly using a radix, you tell parseInt not to try to figure out what numeral system is being used but instead to use the one you specify. Your instinct when typing parseInt should always be to specify the radix; not doing so leaves you open to oddities.