Possible Duplicate:
Leading zero in javascript
Given you have the following JavaScript snippet:
<script>
var x = 013;
console.log(x);
</script>
Why is it that Firebug prints 11?
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stevek-pro
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does it interpret that as octal? – dbeer Oct 17 '11 at 21:36
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4Read: https://developer.mozilla.org/en/JavaScript/Guide/Values%2c_Variables%2c_and_Literals#Integers – Felix Kling Oct 17 '11 at 21:37
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The leading 0 means it's in [Octal](http://en.wikipedia.org/wiki/Octal). – 逆さま Oct 17 '11 at 21:37
6 Answers
4
JavaScript supports the same convention for numeric constants as C and Java (et al), so the leading zero makes that an octal constant. ("13" in base 8 is 8 + 3, or 11.)
Pointy
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1@karim79: Yes you are, but you were a mega-rockstar when you were Simpsonized. ;) – user113716 Oct 17 '11 at 21:43
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The Red Hot Chili Peppers are old too and still rock stars.... at least for me ;) You are never to old to be a rock star! – Felix Kling Oct 17 '11 at 21:43
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@Ӫ_._Ӫ - I de-simponified myself in the hope that a more personal photo would gain me more rep. How wrong I was. :( – karim79 Oct 17 '11 at 21:45
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Because you've specified an octal number, but it displays its decimal representation.
user113716
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It's interpreting it as octal. Any number that begins in zero is interpreted as an octal (base 8) literal, and octal 13 = 8*1+3 = 11 decimal.
Also, good title.
Dan
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It is being interpreted as base 8. And 013 in base 8 is 11 decimal.
In javascript, constant numbers that begin with 0dd or -0dd and are not 0xdd or -0xdd are interpreted as octal (base 8).
You can see it described in the ECMAScript specification on page 231.
jfriend00
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013 is an octal constant - it's interpreted in base 8. 1·8 + 3·1 = 8 + 3 = 11
millimoose
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