How child components communicate with parent components? Facebook ReactJS Interview Question
Inverse data flow - Children communicate with parents by calling functions that are handed to them via props. In the ProductHunt app, when ...

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Inverse data flow - Children communicate with parents by calling functions that are handed to them via props. In the ProductHunt app, when an up-vote was clicked Product didn't do any data management. It was not the owner of its state. Instead, it called a function given to it by ProductList, passing in its id. ProductList was then able to manage state accordingly.