ViewToken object is returned as one of properties in the onViewableItemsChanged callback, for example in FlatList component. It is exported by ViewabilityHelper.js.
Example
Keys and values
index
Unique numeric identifier assigned to the data element.isViewable
Specifies if at least some part of list element is visible in the viewport.item
Item datakey
Key identifier assigned of the data element extracted to the top level.section
Item section data when used withSectionList.
