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

Comments

• 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).

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