react-native/docs/flatlist.md

---
id: flatlist
title: FlatList
layout: docs
category: components
permalink: docs/flatlist.html
next: image
previous: drawerlayoutandroid
---
A performant interface for rendering simple, flat lists, supporting the most handy features:

 - Fully cross-platform.
 - Optional horizontal mode.
 - Configurable viewability callbacks.
 - Header support.
 - Footer support.
 - Separator support.
 - Pull to Refresh.
 - Scroll loading.
 - ScrollToIndex support.

If you need section support, use [`<SectionList>`](docs/sectionlist.html).

Minimal Example:

    <FlatList
      data={[{key: 'a'}, {key: 'b'}]}
      renderItem={({item}) => <Text>{item.key}</Text>}
    />

More complex, multi-select example demonstrating `PureComponent` usage for perf optimization and avoiding bugs.

- By binding the `onPressItem` handler, the props will remain `===` and `PureComponent` will
  prevent wasteful re-renders unless the actual `id`, `selected`, or `title` props change, even
  if the components rendered in `MyListItem` did not have such optimizations.
- By passing `extraData={this.state}` to `FlatList` we make sure `FlatList` itself will re-render
  when the `state.selected` changes. Without setting this prop, `FlatList` would not know it
  needs to re-render any items because it is also a `PureComponent` and the prop comparison will
  not show any changes.
- `keyExtractor` tells the list to use the `id`s for the react keys instead of the default `key` property.


    class MyListItem extends React.PureComponent {
      _onPress = () => {
        this.props.onPressItem(this.props.id);
      };

      render() {
        const textColor = this.props.selected ? "red" : "black";
        return (
          <TouchableOpacity onPress={this._onPress}>
            <View>
              <Text style={{ color: textColor }}>
                {this.props.title}
              </Text>
            </View>
          </TouchableOpacity>
        );
      }
    }

    class MultiSelectList extends React.PureComponent {
      state = {selected: (new Map(): Map<string, boolean>)};

      _keyExtractor = (item, index) => item.id;

      _onPressItem = (id: string) => {
        // updater functions are preferred for transactional updates
        this.setState((state) => {
          // copy the map rather than modifying state.
          const selected = new Map(state.selected);
          selected.set(id, !selected.get(id)); // toggle
          return {selected};
        });
      };

      _renderItem = ({item}) => (
        <MyListItem
          id={item.id}
          onPressItem={this._onPressItem}
          selected={!!this.state.selected.get(item.id)}
          title={item.title}
        />
      );

      render() {
        return (
          <FlatList
            data={this.props.data}
            extraData={this.state}
            keyExtractor={this._keyExtractor}
            renderItem={this._renderItem}
          />
        );
      }
    }

This is a convenience wrapper around [`<VirtualizedList>`](docs/virtualizedlist.html),
and thus inherits its props (as well as those of `ScrollView`) that aren't explicitly listed
here, along with the following caveats:

- Internal state is not preserved when content scrolls out of the render window. Make sure all
  your data is captured in the item data or external stores like Flux, Redux, or Relay.
- This is a `PureComponent` which means that it will not re-render if `props` remain shallow-
  equal. Make sure that everything your `renderItem` function depends on is passed as a prop
  (e.g. `extraData`) that is not `===` after updates, otherwise your UI may not update on
  changes. This includes the `data` prop and parent component state.
- In order to constrain memory and enable smooth scrolling, content is rendered asynchronously
  offscreen. This means it's possible to scroll faster than the fill rate ands momentarily see
  blank content. This is a tradeoff that can be adjusted to suit the needs of each application,
  and we are working on improving it behind the scenes.
- By default, the list looks for a `key` prop on each item and uses that for the React key.
  Alternatively, you can provide a custom `keyExtractor` prop.

Also inherits [ScrollView Props](docs/scrollview.html#props), unless it is nested in another FlatList of same orientation.

### Props

- [`numColumns`](docs/flatlist.html#numcolumns)




### Methods

- [`scrollToEnd`](docs/flatlist.html#scrolltoend)
- [`scrollToIndex`](docs/flatlist.html#scrolltoindex)
- [`scrollToItem`](docs/flatlist.html#scrolltoitem)
- [`scrollToOffset`](docs/flatlist.html#scrolltooffset)
- [`recordInteraction`](docs/flatlist.html#recordinteraction)
- [`flashScrollIndicators`](docs/flatlist.html#flashscrollindicators)


### Type Definitions

- [`Props`](docs/flatlist.html#props)
- [`DefaultProps`](docs/flatlist.html#defaultprops)




---

# Reference

## Props

### `numColumns`



| Type | Required |
| - | - |
|  | No |






## Methods

### `scrollToEnd()`

```javascript
scrollToEnd([params]: object)
```

Scrolls to the end of the content. May be janky without `getItemLayout` prop.



---

### `scrollToIndex()`

```javascript
scrollToIndex(params: object)
```

Scrolls to the item at the specified index such that it is positioned in the viewable area
such that `viewPosition` 0 places it at the top, 1 at the bottom, and 0.5 centered in the
middle. `viewOffset` is a fixed number of pixels to offset the final target position.

Note: cannot scroll to locations outside the render window without specifying the
`getItemLayout` prop.



---

### `scrollToItem()`

```javascript
scrollToItem(params: object)
```

Requires linear scan through data - use `scrollToIndex` instead if possible.

Note: cannot scroll to locations outside the render window without specifying the
`getItemLayout` prop.



---

### `scrollToOffset()`

```javascript
scrollToOffset(params: object)
```

Scroll to a specific content pixel offset in the list.

Check out [scrollToOffset](docs/virtualizedlist.html#scrolltooffset) of VirtualizedList



---

### `recordInteraction()`

```javascript
recordInteraction()
```

Tells the list an interaction has occurred, which should trigger viewability calculations, e.g.
if `waitForInteractions` is true and the user has not scrolled. This is typically called by
taps on items or by navigation actions.



---

### `flashScrollIndicators()`

```javascript
flashScrollIndicators()
```

Displays the scroll indicators momentarily.



## Type Definitions

### Props

| Type |
| - |
| IntersectionTypeAnnotation |




---

### DefaultProps

| Type |
| - |
| TypeofTypeAnnotation |