react-native/docs/Basics-Component-ListView.md
Joel Marcey 6668cd2129 Add ScrollView to Basics docs
Summary:
Add basic information about the generic `ScrollView` -- talk a bit about how it renders elements and a quick compare against something like a `ListView`. Provide a simple example.

Fixes #8261
Closes https://github.com/facebook/react-native/pull/8266

Differential Revision: D3465105

Pulled By: JoelMarcey

fbshipit-source-id: 3a2e1eac6e877669763fc6b8bb0fc78ebe870ab1
2016-06-21 13:28:30 -07:00

2.1 KiB

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basics-component-listview ListView docs Basics docs/basics-component-listview.html basics-integration-with-existing-apps

On mobile devices, lists are a core element in many applications. The ListView component is a special type of View that displays a vertically scrolling list of changing, but similarly structured, data.

ListView works best for possibly lengthy datasources (e.g., from an endpoint or database), where the number of items may not be known a priori.

Unlike the more generic ScrollView, the ListView only renders elements that are currently showing on the screen, not all the elements at once.

The ListView component requires two properties, dataSource and renderRow. dataSource is the actual source of information that will be part of the list. renderRow takes the data and returns a renderable component to display.

This example creates a simple ListView of hardcoded data. It first initializes the datasource that will be used to populate the ListView. Then it renders that ListView with that data.

A rowHasChanged function is required to use ListView. Here we just say a row has changed if the row we are on is not the same as the previous row.

import React from 'react';
import { AppRegistry, Text, View, ListView} from 'react-native';

var SimpleList = React.createClass({
  // Initialize the hardcoded data
  getInitialState: function() {
    var ds = new ListView.DataSource({rowHasChanged: (r1, r2) => r1 !== r2});
    return {
      dataSource: ds.cloneWithRows(['John', 'Joel', 'James', 'Jimmy', 'Jackson', 'Jillian', 'Julie'])
    };
  },
  render: function() {
    return (
      <View>
        <ListView
          dataSource={this.state.dataSource}
          renderRow={(rowData) => <Text>{rowData}</Text>}
        />
      </View>
    );
  }
});

// App registration and rendering
AppRegistry.registerComponent('MyApp', () => SimpleList);