How to Pass "NotIn" values in report query string parameter?

I have embedded the report in the web app through app only scenario

for exporting the report in PDF/PPT format using exportToFile API, I want to pass the report level filters based on selected values from slicers.

I am able to get all the filtered items from Slicers using visual.getSlicerState() method by javascript code.

but when the user will deselect some of the values from the slicer, visual.getSlicerState() method will return the list of those excluded values with "NotIn" operator.

As per the Export API article, we have to pass the report filters in the format of query string parameter (URL Filters).

and if we look at the query string parameter article, there is no such operator available for "NotIn".

so, I want to pass all the slicer values excluding the deselected values using "In" operator.

but somehow I am not able to access the full list of slicer drop-down values.

does anyone have any idea how to get the full list of slicer drop-down values using javascript?

or

how to pass "NotIn" in query string parameter filters?

Thanks in advance