CODEWITHSUNDEEP
reactjsreact-reduxreact-hooks
Ted
Ted

Reputation: 395

Stop scroll bar from moving to top when rerendering reactjs

I am trying to create a panel where a list of item is presented, once an item is clicked, the right hand side should display the item selected. The left hand side should contain a list of items. The list of items can be very long therefore, i have limited the max height of the list such that when it exceeds this height, it will create a scroll bar so user can scroll down to see the rest of the list. The problem is, whenever an item at the bottom of the list is clicked, the list automatically scrolls back up to the top. I have a feeling that this is due to the fact that I am using a state to pass the item around, and when the item is changed, it causes a re-render thus "reseting" the list. Can someone give me a suggestion as to how i can stop this from happening? Any pointers would be greatly appreciated!

Here is the sandbox: https://codesandbox.io/s/sad-archimedes-3u4k0?file=/src/App.js

ex/ scroll to the bottom and click "random30" and the list goes back up to "random1"

Upvotes: 1

Views: 4148

Answers (1)

awran5
awran5

Reputation: 4536

This happens because you placed a component EventListContainer inside of EventsList component which will lead to "re-render" every time you update the state.

You can just move ScrollContainer directly inside the EventsList component return:

return (
  <ListContainer>
    <ScrollContainer>
      {eventListSorted.map(event => {
        return (
          <EventContainer
            onClick={e => {
              onSelect(event);
              setSelectedEvent(event);
            }}
            selected={selectedEvent ? selectedEvent.id === event.id : false}
          >
            {event.uiString}
          </EventContainer>
        );
      })}
    </ScrollContainer>
  </ListContainer>
);

Also you better move the eventListSorted array outside the EventsList component.

sandbox example.

Upvotes: 3

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