JavaScript - parseInt inconsistent in different browsers

Question

EDIT: The problem was I wasn't specifying a base when I used parseInt. I want to understand exactly why this happened - I'll reward the answer to anyone who can tell me why this only created a problem for the values 08 and 09 in firefox!

I have a 2-dimensional array of integers stored as a JSON object in a MySQL database.

When I request this object via jquery's ajax, the JSON validates - it also passes through JSONLint without incident. I then translate it into a 2-dimensional javascript array, using parseInt to translate the string-only JSON keys into integer keys for the array.

This works just fine, on almost all browsers/platforms:

Original JSON:

....
"07": [0, 1...
"08": [0, 1...
"09": [1, 1...
"10": [1, 0...
....

For-loop output (Safari/Chrome, OSX):

JSON Key (parseInt value): [array]
....
07 (7): [0, 1...
08 (8): [0, 1...
09 (9): [1, 1...
10 (10): [1, 0...
....

For-loop output (Firefox OSX, iOS):

JSON Key (parseInt value): [array]
....
07 (7): [0, 1...
08 (0): [0, 1...
09 (0): [1, 1...
10 (10): [1, 0...
....

...what the heck? These keys (8 and 9) are the only ones that don't properly pass though parseInt, and it happens very consistently. I've verified that the JSON array comes into all browsers intact and unmodified - the fact that the keys remain 08 and 09 is evidence of that. However, as soon as 08 and 09 pass through parseint, they return 0. 18 and 19 pass properly, as do 28 and 29. There are no stray spaces, non-ascii characters, or anything else surrounding these two keys that could cause them to be read improperly. I'm completely stumped.

You can find my full JSON here. What am I missing?

Alternatively, if there's a way I can circulvent this completely, I'm willing to consider it. Thanks for the help, this is driving me nuts!

Are you using `parseInt(value)` or `parseInt(value, 10)`? Post your JS code. — Blender, Feb 16 '13 at 23:10
was using parseInt(value) - parseInt(value, 10) seems to have resolved it — CodeMoose, Feb 16 '13 at 23:14
Very simple solution here. Never call `parseInt()` without passing the radix or use one of the other ways to convert to a number. — jfriend00, Feb 16 '13 at 23:29

Bhushan Firake · Accepted Answer · 2013-02-16T23:24:23.137

3

The base for strings starting with 0 can be octal (when a radix is not specified - and depending on the browser).

You are looking for:

parseInt("09", 10);// parseInt("09")=0
parseInt("08", 10);// parseInt("08")=0

WHY?

If radix is undefined or 0, JavaScript assumes the following:

If the input string begins with "0x" or "0X", radix is 16 (hexadecimal).

If the input string begins with "0", radix is eight (octal). This feature is non-standard, and some implementations deliberately do not support it (instead using the radix 10). For this reason always specify a radix when using parseInt.

If the input string begins with any other value, the radix is 10 (decimal).

Both parseInt('08') and parseInt('09') return zero because the function tries to determine the correct base for the numerical system used. In Javascript numbers starting with zero are considered octal and there's no 08 or 09 in octal, hence the problem.

See the documentation for parseInt:

   var test = parseInt(value, 10);

You have to tell it you want the value of the input you are targeting.

And also, always provide the second argument (radix) to parseInt. It tries to be too clever and autodetect it if not provided and can lead to unexpected results.

Providing 10 assumes you are wanting a base 10 number.

edited Feb 16 '13 at 23:24

answered Feb 16 '13 at 23:10

Bhushan Firake

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I don't know what that means. Vanilla use of parseInt works fine in all browsers - this only happens in firefox with the values 08 and 09. – CodeMoose Feb 16 '13 at 23:11
@CodeMoose - read https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/parseInt – j08691 Feb 16 '13 at 23:15
@CodeMoose: FF might be interpreting them as base 8 numbers. – Blender Feb 16 '13 at 23:16
@CodeMoose Put radix in your parseInt function as I have passed 10...by default it is 8 – Bhushan Firake Feb 16 '13 at 23:17
@Blender: thanks for the input - but even if that resulted in 08 being interpreted as 0, wouldn't that have resulted in 09 returning 1? – CodeMoose Feb 16 '13 at 23:18
@CodeMoose: No, because `09` is not a valid octal number. Just like `102` is not valid binary. – Felix Kling Feb 16 '13 at 23:19
Ah, I think I undertsand now. I was making more than a couple assumptions. Thanks for walking me through it! – CodeMoose Feb 16 '13 at 23:20
@CodeMoose See my update...Any chance of my answer being rewarded? – Bhushan Firake Feb 16 '13 at 23:26
@BhushanFirake Considering the effort you put into it, and considering there aren't any other answers, I'd say so – CodeMoose Feb 16 '13 at 23:38

JavaScript - parseInt inconsistent in different browsers

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