I need to writ a script that distinguishes between a file field being empty or not. This is needed to generate a page displaying or not the image contained in that file...

The issue I am having is that non of these options seem to work:

if (file_field=null) {script}

if (file_field="") {script}

in both cases, the result of the if statement is true even though there is no file contained in the field.

would you please let me know how to make the if statement work fine and return false when there is no file in the field?

Thanks

Luis