Light Refactoring - Amazon Vega Docs

Before we start, let’s do some light refactoring by optimising our imports. In Part 1, when we needed components and screens, we imported them on separate lines. As our app grows, there could be many import statements making the code harder to read. We can reduce the number of import statements, by creating an index.ts file in each folder that lists the components/screens in each folder. It will list each component/screen as named exports, which can be imported on one line. This is the same syntax we use to import components, such as View and Text from ‘react-native’. For example, import { View, Text } from 'react-native'.

Add index file to components folder

First we will create an index.ts for the components folder.

In the components folder and create a new file called index.ts. We use the .ts extension, because this is a pure TypeScript file that doesn’t contain any JSX.

src/
├── components/
│   ├── Header.tsx
│   ├── VideoCard.tsx
|   └── index.ts
└── App.tsx

Open index.ts and add import statements for every component in the components folder.
Add an export statement that lists each component.

The index.ts file should look like this:

import Header from './Header';
import VideoCard from './VideoCard';

export {
    Header,
    VideoCard
}

Import components

Next, we need to update LandingScreen.tsx to use the new imports approach.

In the LandingScreen.tsx remove the import statements for Header and VideoCard.
Add one import statement that adds the components from index.ts. Note that we only need to specify the import from the components folder, as the index.ts file will be read in this folder to find the named exports (Header, VideoCard).

The import statements in LandingScreen.tsx should look like this:

import React, {useState, useEffect} from 'react';
import {FlatList, StyleSheet, View} from 'react-native';
import {Header, VideoCard} from '../components';

Add index file to screens folder

Now we will repeat the process for the screens folder.

Create a file called index.ts in the screens folder.

src/
├── screens/
│   ├── LandingScreen.tsx
|   └── index.ts
└── App.tsx

Open index.ts and add import statements for every component in the screens folder.
Add an export statement that lists each component.

The index.ts file should look like this:

import LandingScreen from './LandingScreen';

export {
    LandingScreen,
}

Import screens

Now we need to update the import statements in App.tsx.

Open App.tsx.
Remove the import statement for LandingScreen.
Add one import statement that adds the LandingScreen screen from the screens folder.

The import statements in App.tsx should now look like this:

import * as React from 'react';
import {LandingScreen} from './screens';

Reload the app and verify that everything renders the same.

This refactoring may not seem like much, but as you build complex applications with many components and screens, this will help you reduce the number of import statements at the top of each file.

​Add index file to components folder

​Import components

​Add index file to screens folder

​Import screens

Add index file to components folder

Import components

Add index file to screens folder

Import screens