Why does my javascript Catch block not execute?

Question

I feel silly asking this, I must be missing something obvious.

My javascript looks as follows...

function onNewItemClick(event)
{
    alert('ello!');
    try
    {
        var xx = 111/0;
    }
    catch(exc)
    {
        alert('fff');
    }
}

alert('ello!') works like it should, but the alert('fff') in the Catch block never gets called. What am I doing wrong here?

Christian C. Salvadó · Accepted Answer · 2009-12-04 16:07:31Z

7

The catch doesn't executes because division by zero doesn't rises an exception, it simply sets you xx variable to Infinity.

To check if a number is finite you can use the isFinite function:

if (!isFinite(xx)) {
  //...
}

answered Dec 4, 2009 at 16:07

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3 Comments

Or to undefined depending on the browser.

Ha ha, that's what happens when a .NET junkie ventures into the javascript world :) Thanks!

@willem: You're welcome!, @jitter: That behavior is pretty much standard (see ECMA-262 Section 11.5.2) is.gd/5clge (PDF)