Javascript variable with leading zeroes - Stack Overflow

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Javascript behaves differently with values having leading zeroes. alert(b) - prints different value.

var a = 67116;
var b = 00015;
alert(a);
alert(b);

I am more interested to know What conversion is applied here by javascript inside alert(b) ? (If i have them in double quotes. They work fine.)

Javascript behaves differently with values having leading zeroes. alert(b) - prints different value.

var a = 67116;
var b = 00015;
alert(a);
alert(b);

I am more interested to know What conversion is applied here by javascript inside alert(b) ? (If i have them in double quotes. They work fine.)

• javascript
• leading-zero

Share Improve this question Follow edited Sep 9, 2014 at 15:17 tshepang 12.5k2525 gold badges9797 silver badges139139 bronze badges asked Jun 14, 2013 at 17:39 KrishnamKrishnam 84911 gold badge1515 silver badges2121 bronze badges 4

• Yeah, what the hell is going on here: jsfiddle/watson/4qsvQ – dezman Commented Jun 14, 2013 at 17:42
• If they are in quotes, it is a string and will be read literally. – dezman Commented Jun 14, 2013 at 17:45
• @Kris , your nickname is the same of my exgf, i'm depressed now :/ ... is that weird? – Jon Commented Jun 14, 2013 at 17:57
• 1 May be you are too weird...i better say, you are her EX. i rather place you in variable b..that will give you new decimal life. – Krishnam Commented Jun 14, 2013 at 18:14

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3 Answers 3

Sorted by: Reset to default 3

var b = 00015

is an octal number

see this question for solution

A leading 0 makes the value an octal literal, so the value you put will be interpreted as a base 8 integer.

In other words, 015 will be equivalent to parseInt('15', 8).

As the other answers said, the leading zeroes make the number an octal literal. The decimal representation of the octal "15" is "13".

Note that there is no reason to use leading zeroes on number literals unless you really really want them to be interpreted as octals. I mean, don't use var b = 00015. If you're getting that value from user input, then it will be a string (i.e. "00015"), and you can convert to a decimal number with parseInt:

var b = "00015"; // or var b = document.getElementById('some_input').value
var numB = parseInt(b, 10); // 15

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