parseInt("08") returns 0

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Workarounds for JavaScript parseInt octal bug

I've been working on a javascript function, setting date objects by declaring the year, month & date. However, when the month has a value of 08 or 09, 0 is returned when using parseInt(). See below:

parseInt("01") //returns 1
parseInt("02") //returns 2
parseInt("03") //returns 3
parseInt("04") //returns 4
parseInt("05") //returns 5
parseInt("06") //returns 6
parseInt("07") //returns 7
parseInt("08") //returns 0?
parseInt("09") //returns 0?
parseInt("10") //returns 10

I've created a jsFiddle to demonstrate this issue:

http://jsfiddle.net/GhkEf/

Why does parseInt("08") and parseInt("09") return 0?

http://stackoverflow.com/questions/6410009/what-do-you-think-parseint08-will-return?rq=1 — gray state is coming, Sep 07 '12 at 13:13
Read the MDN docs: https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/parseInt This issue is well documented — Šime Vidas, Sep 07 '12 at 13:14
@ŠimeVidas Ahh of course! Friday afternoon hiccup! Thanks for your responses — Curtis, Sep 07 '12 at 13:15
I voted to reopen because Unlike [How do I work around JavaScript's parseInt octal behavior?](https://stackoverflow.com/questions/850341/how-do-i-work-around-javascripts-parseint-octal-behavior) this question is more well suited at people who don't already know that this is due to octal notation — Sam I am says Reinstate Monica, Feb 06 '19 at 00:01

score 45 · Accepted Answer · answered Sep 07 '12 at 13:13

45

That's because numbers started with 0 are considered to be octal. And 08 is a wrong number in octal.

Use parseInt('09', 10); instead.

answered Sep 07 '12 at 13:13

zerkms

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This occur just on IE8. – thiago.lenz Jul 09 '13 at 14:05

Some Guy · Answer 2 · 2014-03-13T10:45:48.433

5

It's being parsed as an octal number. Use the radix parameter in parseInt.

parseInt('08', 10);

An update: As of ES5, browsers should not have this bug. Octal literals require to be in the form 0o12 to be considered Octal numbers. 08 by default is now considered a decimal number in ES5, however, all browsers may not support this yet, so you should continue to pass the radix parameter to parseInt

edited Mar 13 '14 at 10:45

answered Sep 07 '12 at 13:13

Some Guy

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score 1 · Answer 3 · answered Sep 07 '12 at 13:14

1

You can fix this by including the radix, e.g.:

parseInt("08", 10); // outputs 8

answered Sep 07 '12 at 13:14

Paddy

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score 1 · Answer 4 · answered Sep 07 '12 at 13:14

1

You need to add a radix of ten:

parseInt("08", 10);

Some implementations default to octal.

answered Sep 07 '12 at 13:14

Sepster

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parseInt("08") returns 0

4 Answers4