Hi,
I would like to show a leading "+" in front of positive numbers in a column which is showing (numeric) values.

I already tried the following:
a) formatCurrency with a prefix "+". But this is not condtitional to positive numbers.
b) In my current solution I convert the numbers to characters "manually" first. But now I'd like to filter this column "numerically" (slider). This does not seem to be possible.

Then, you should do filtering at first and converting at last.

It is kinda strange that someone need a "+" symbol to show a number being positive in data frame. Commonly I see that on a plot instead. Could you share the reason?

Whatever the reason for prefixing positive values with a "+", I put together a small example demoing how to do so using DataTable's createdRow option. It is important to note my example does this cell by cell. In the example i refers to the index of each column in a row, so if particular columns need to be ignored add logic to ignore certain values of i. Remember, in JavaScript indexing starts at 0, so your first column is column 0.

@nteetor Thanks, very much. That's exactly what I was looking for.
Had to modify your example slightly since there seems to be a problem with the lambda function: