Possible to use output File output node only if condition is true?

Is it possible to make a condition before a file output node, so that only if the condition is true, files are output?

How do you plan to use this feature? Often there is no need for obscure features and problem is solved somewhere else.

What you can do is add your condition as nodes so that true outputs 1 and false is 0 and multiply your image data with this before write node. When using a file format that has compression this results in very small file size when condition is false and you can manually delete these frames in output folder (sort by size)

Sounds like a good workaround! I wanted to try to use levels to sort out images that differ too much. Another question that pops up is if you can somehow see the numerical output of levels or other nodes?

Yes, I can have a wild idea and want to check it out. Then its fantastic to get feedback on that, even if it is that the idea is all wrong, so thank you guys for that.