parseInt("08")（无基数）在 Chrome 中返回 8，在 Firefox 中返回

Question

I was showing my colleague why you must always specify a radix with parseInt and I was surprised to see that parseInt("08") returns 8 in both the console of Firefox and Chrome

shouldn't it be an octal and return 0 ?

Answer 1

This is a question for old timers

Before 2011, parseInt("08") used to return 0 as parseInt would determine 08 was an octal as it started with an 0

As @Pointy pointed out, the radix being octal for string starting with a 0 has been deprecated for a long time now

As the radix used in this case depends on the implementation, you should specify a radix ( parseInt("08", 10) because there is no way to be sure whether the octal or decimal algorithm will be used

Sources:

• https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/parseInt#Description
• https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/parseInt#Browser_compatibility