Unlock the Power of React Native’s FlatList Component
When building mobile apps with React Native, you’ll inevitably encounter lists of data that need to be displayed. Whether it’s a list of contacts, users, or activities, displaying large datasets can be a daunting task. That’s where the FlatList component comes in – a powerful tool designed to handle large quantities of scrollable list items with ease.
What is the FlatList Component?
The FlatList component is a performance-optimized solution for displaying large datasets. Under the hood, it leverages the ScrollView component, but with added features that enhance performance. These features include only rendering visible items on the screen and updating only changed items. This makes the FlatList component ideal for handling large datasets that may change over time.
Getting Started with FlatList
To use the FlatList component, you need to know about two essential props: data and renderItem. The data prop is an array of data used to create the list, while the renderItem prop is a callback function that accepts individual items from the data prop and renders a component for each item.
Basic Usage Example
Let’s create a simple example to demonstrate how to use the FlatList component. Suppose we have an array of countries and want to display them in a list. We’ll create a Country component and use the FlatList component to render the list.
“`jsx
import React, { useState } from ‘eact’;
import { FlatList } from ‘eact-native’;
const App = () => {
const [countries, setCountries] = useState([
{ name: ‘USA’ },
{ name: ‘Canada’ },
{ name: ‘Mexico’ },
]);
const renderItem = ({ item }) => {
return
};
return (
);
};
“`
Fetching Data from an API
In a real-world scenario, you’ll often need to fetch data from a backend service. Let’s explore how to use the FlatList component to display data fetched from an API.
We’ll use the JSON placeholder API to fetch user info and display it in a list. We’ll also add a header component and use the react-native-elements library for styling.
“`jsx
import React, { useState, useEffect } from ‘eact’;
import { FlatList } from ‘eact-native’;
import { Header } from ‘eact-native-elements’;
const App = () => {
const [users, setUsers] = useState([]);
const [refreshing, setRefreshing] = useState(false);
useEffect(() => {
fetch(‘https://jsonplaceholder.typicode.com/users’)
.then((response) => response.json())
.then((data) => setUsers(data));
}, []);
const renderItem = ({ item }) => {
return
};
const handleRefresh = () => {
setRefreshing(true);
fetch(‘https://jsonplaceholder.typicode.com/users’)
.then((response) => response.json())
.then((data) => {
setUsers(data);
setRefreshing(false);
});
};
return (
);
};
“`
Pull to Refresh and Pagination
Two essential features to consider when working with lists are pull-to-refresh and pagination. Pull-to-refresh allows users to refresh the data on the screen by pulling down on the list, while pagination enables you to load more data as the user reaches the end of the list.
To implement pull-to-refresh, we’ll use the refreshing and onRefresh props. The refreshing prop indicates whether the list is currently refreshing, while the onRefresh prop is a callback function that’s called when the user pulls to refresh.
For pagination, we’ll use the onEndReached prop to detect when the user reaches the end of the list. We’ll then fetch more data and update the list accordingly.
By mastering the FlatList component and its features, you’ll be able to create high-performance, user-friendly lists that enhance the overall user experience of your React Native app.