react-native/docs/Basics-Component-ListView.md
Devin Abbott 6c5f532591 Add docs pages for basics: Dimensions and Layout
Summary:
These pages should sufficiently give a beginner enough information to make most layouts in React Native. They should go after the basics-style page, whenever that is ready.

Having a single page for Layout was too much, so I split it into two: Dimensions and Layout.

![dimensions react native a framework for building native apps using react](https://cloud.githubusercontent.com/assets/1198882/16311045/c6918b64-3923-11e6-8cc9-daeda9eb40e6.png)

![layout react native a framework for building native apps using react](https://cloud.githubusercontent.com/assets/1198882/16310233/9a66405a-3920-11e6-9ef6-1594f7228e83.png)

lacker
Closes https://github.com/facebook/react-native/pull/8364

Differential Revision: D3477147

Pulled By: lacker

fbshipit-source-id: 1ef31ac0a64e43166a7581b38fa8263282672eeb
2016-06-23 11:58:54 -07:00

2.2 KiB

id title layout category permalink next
basics-component-listview ListView docs The Basics docs/basics-component-listview.html basics-dimensions

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 source of information for the list. renderRow takes one item from the source and returns a formatted component to render.

This example creates a simple ListView of hardcoded data. It first initializes the dataSource that will be used to populate the ListView. Each item in the dataSource is then rendered as a Text component. Finally it renders the ListView and all Text components.

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, ListView, Text, View } from 'react-native';

var AwesomeList = 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 style={{paddingTop: 22}}>
        <ListView
          dataSource={this.state.dataSource}
          renderRow={(rowData) => <Text>{rowData}</Text>}
        />
      </View>
    );
  }
});

// App registration and rendering
AppRegistry.registerComponent('AwesomeProject', () => AwesomeList);