Shopify/flash-list

Installation

Add the package to your project via yarn add @shopify/flash-list and run pod install in the ios directory.

Usage

We recommend reading the detailed documentation for using FlashList here.

But if you are familiar with FlatList, you already know how to use FlashList. You can try out FlashList by changing the component name and adding the estimatedItemSize prop or refer to the example below:

import React from "react";
import { View, Text } from "react-native";
import { FlashList } from "@shopify/flash-list";

const DATA = [
  {
    title: "First Item",
  },
  {
    title: "Second Item",
  },
];

const MyList = () => {
  return (
    <FlashList
      data={DATA}
      renderItem={({ item }) => <Text>{item.title}</Text>}
      estimatedItemSize={200}
    />
  );
};

To avoid common pitfalls, you can also follow these steps for migrating from FlatList, based on our own experiences:

1. Switch from FlatList to FlashList and render the list once. You should see a warning about missing estimatedItemSize and a suggestion. Set this value as the prop directly.
2. Important: Scan your renderItem hierarchy for explicit key prop definitions and remove them. If you’re doing a .map() use indices as keys.
3. Check your renderItem hierarchy for components that make use of useState and verify whether that state would need to be reset if a different item is passed to that component (see Recycling)
4. If your list has heterogenous views, pass their types to FlashList using getItemType prop to improve performance.
5. Do not test performance with JS dev mode on. Make sure you’re in release mode. FlashList can appear slower while in dev mode due to a small render buffer.

App / Playground

The fixture is an example app showing how to use the library.