JavaScript function parseInt() doesn't parse numbers with leading 0 correctly

Asked 19/12, 2010 at 4:4 Answered 19/12, 2010 at 4:10

I have some zeros prior to a positive integer. I want to remove the zeros so only the positive integer remains. Like '001' will only be '1'. I thought the easiest way was to use parseInt('001'). But what I discovered is that it don't works for the number 8 and 9. Example parseInt('008') will result in '0' instead of '8'.

Here are the whole html code:

<html> <body>
<script>
var integer = parseInt('002');
document.write(integer);

</script>
</body> </html>

But can I somehow report this problem? Do anyone know an another easy workaround this problem?

Gaud answered 19/12, 2010 at 4:4 Comment(1)

also, stripping leading zeros by using parseInt('008').toString() is very clumsy, consider using RegExp instead – Otiliaotina 19/12, 2010 at 4:44

This is documented behavior: http://www.w3schools.com/jsref/jsref_parseInt.asp

Strings with a leading '0' are parsed as if they were octal.

Yablon answered 19/12, 2010 at 4:6 Comment(2)

MDN docs are generally of much higher quality than their w3schools counterparts. Here's the relevant MDN page. – Nth 14/12, 2012 at 19:19

FireFox 21 has curiously decided to remove this functionality. Chrome has apparently been that way for a while: stackoverflow.com/questions/14542377 – Uppermost 15/5, 2013 at 0:15

You have to specify the base of the number (radix)

parseInt('01', 10);

Pirandello answered 19/12, 2010 at 4:7 Comment(1)

Yep, and a JS code quality tool like JSLint (jslint.com) can give you a heads up about it :) – Zygapophysis 19/12, 2010 at 4:13

This is documented behavior: http://www.w3schools.com/jsref/jsref_parseInt.asp

Strings with a leading '0' are parsed as if they were octal.

Yablon answered 19/12, 2010 at 4:6 Comment(2)

MDN docs are generally of much higher quality than their w3schools counterparts. Here's the relevant MDN page. – Nth 14/12, 2012 at 19:19

FireFox 21 has curiously decided to remove this functionality. Chrome has apparently been that way for a while: stackoverflow.com/questions/14542377 – Uppermost 15/5, 2013 at 0:15

Number prefixed with zero is parsed as octal.

Draggletailed answered 19/12, 2010 at 4:6 Comment(1)

That's not the whole story -- it's browser and version dependent. – Nth 14/12, 2012 at 19:20

This is not actually a bug. For legacy reasons strings starting with 0 are interpreted in octal, and in octal there is no digit 8. To work around this you should explicitly pass a radix (i.e. parseInt("008", 10)).

Chemash answered 19/12, 2010 at 4:10 Comment(0)

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