How to know the state of scroll (up or down) in FlatList?

问题

How to know the state of the scroll in FlatList? Like scrolling up or scrolling down? I want to know the state scrolling up or down to show or hide header in FlatList.

回答1:

Use the onScroll property as below. (Official)

<ScrollView onScroll={this._onScroll} />


_onScroll = (event) {
    console.log(event.nativeEvent.contentOffset.y);
},

And for guarantee getting the value of scrolling's last frame, you need to set a property scrollEventThrottle={16}.

回答2:

Actually, the FlatList component can use ScrollView props so you can use below code to find out your Y position of FlatList scrollbar:

<FlatList onScroll={(e) => console.log(e.nativeEvent.contentOffset.y)} ...

You should write it on some variable and compare it with the latest change, then you can understand scrollbar moves to down or up.

Hint: It starts from zero.

回答3:

Normally, the header is called StickyHeader. And there is already a option called stickyHeaderIndices which takes the index of child to make sticky header.

Official

<ScrollView
  stickyHeaderIndices={[1]}
>

来源：https://stackoverflow.com/questions/53900881/how-to-know-the-state-of-scroll-up-or-down-in-flatlist