Javascript nuances

Posted on Tuesday, November 20, 2007

Oh Javascript... you can't be intuitive can you?

I want to see if a function exists and then call it -

if(decrementComments)
decrementComments();

Wrong.

if(typeof decrementComments == 'function')
decrementComments();

Right.

Graffiti users of the world can have comments on their posts now. :)

Jayme

Ben Tiedt on 11.20.2007 at 2:55 PM
What's wrong with #1? I've used this hundreds of times. While its true that it only checks that the variable exists and is non-null (or zero or false), it should work for simple checks.
Jayme on 11.20.2007 at 3:17 PM
With #1, I get the following error if the function is not defined (IE and FF).

decrementComments is not defined

Line: if(decrementComments)

If the function is there, it works fine.

Jayme
Ben Tiedt on 11.20.2007 at 4:13 PM
Try if(window.decrementComments) instead -- when I've used this, it has always been against a member variable such as if(this._functionName).
steve on 6.15.2009 at 9:27 PM
thanks for shared