Beware the leading zero in Javascript parseInt()!

Exhibit A,

parseInt('01'); //equals 1
parseInt('02'); //equals 2
parseInt('03'); //equals 3
parseInt('04'); //equals 4
parseInt('05'); //equals 5
parseInt('06'); //equals 6
parseInt('07'); //equals 7
parseInt('08'); //equals 0 !!
parseInt('09'); //equals 0 !!

When Javascript encounters a leading zero it assumes an octal number. So when it sees 08 or 09 then there are problems.

The fix is to add the radix to the function call,

myInt = parseInt('08',10); //equals 8

Why Aren’t You Using FireBug?

I’ve been using the Firefox browser addon called FireBug for a while now and am amazed at how helpful it is. If you’re a web developer, and especially if you use JavaScript and AJAX methods, you should be using it.

For example, while developing I like to add in timers to PHP based pages to show how long things are taking. This way if a SQL statement needs some fine-tuning or a change slows things down I can see it happen. FireBug extends this to the entire page and the HTTP traffic. Here’s what happens when I load a page that has a few JavaScript calls, small images and a single CSS link in it,

Straight away it’s obvious what’s taking up the bulk of the time – those two library calls. Once I take those out of the equation the load time drops to under a second. And through all this the PHP timer function only shows me how long the server-side work is taking.

With FireBug I know who (in a geeky code way) is doing what and with who and I can act on it. Now that’s helpful.