joshwnj / react-visibility-sensor

Sensor component for React that notifies you when it goes in or out of the window viewport.
MIT License
2.33k stars 195 forks source link

No handler for determining visibility of elements that never change visibility #174

Open bmaximilian opened 4 years ago

bmaximilian commented 4 years ago

Problem

Assume having a list of elements that should be checked in the interval but are in the middle of a scroll container so the visibility will never change. That won't trigger the onChange handler. But the use case of the application won't allow to expect that the element is visible from beginning (so we could check at render) and a callback needs to be called when it is visible for a certain time. The callback could not be called in the render method because it affects the performance and should be called when the check is done. Such a handler is not implemented.

Suggestion

Introduce a onCheck prop where a callback can be registered that is called after a check is done (with the isVisible, even if it didn't change).