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JavaScript

Posted by Jon Amar
Jon Amar
558 Points

parseInt not returning octal number

This lesson: JavaScript Foundations > Numbers > Parsing Numbers From Strings

This code:

var j = parseInt("012");

In the video, "j" returns a value of "10" because prepending "12" with a zero indicates that this string should be interpreted as an octal (when it is converted into an integer).

My console (latest versions of Safari & Chrome) is returning "12" (the integer). i.e. it seems to be ignoring the octal and treating the integer as a decimal number. 

var x = 012; // this does get interpreted as an octal and returns 10

Interestingly, Firefox does interpret "j" as an octal. Is this simply a browser issue? Any idea what's going on?

Thanks !

2 Answers

James Barnett
James Barnett
39,199 Points
James Barnett
James Barnett
39,199 Points

You can save yourself the headache by explicitly specifying the base you want

To make sure a number is interpreted as octal just explicitly specify the base

var j = parseInt ('11', 8); //that's 11 in octal or 9 in decimal

Alternatively if you want to use a leading zero with a decimal number, just specify the base there as well.

var j = parseInt('012',10); //that's 12 in decimal

Jon Amar
Jon Amar
558 Points
Jon Amar
Jon Amar
558 Points

Thanks James. That life-saving tip is actually in the lesson as well. And as I learn to code and make things for real-life, I will certainly specify the base.

I guess what I was wondering is whether it was just a browser bug or if I was doing something wrong.

My research leads me to believe browser bug / inconsistencies between browsers. But I was hoping someone with more experience than I could weigh in.