Fetch API for GET requests in React Native - UI Render Trace

Component - Fetch API for GET requests

This React Native component fetches data from a web address using the Fetch API with a GET request. It shows the data on the screen or a loading message while waiting.

Widget Tree

View
├─ Text (title)
├─ Button (Fetch Data)
└─ Text (data or loading message)

The main container is a View. Inside it, a Text shows a title. Below is a Button that triggers the data fetch. Finally, another Text shows the fetched data or a loading message.

Render Trace - 4 Steps

Step 1: View

Step 2: Text (title)

Step 3: Button

Step 4: Text (data or loading)

State Change - Re-render

Trigger:User presses the 'Fetch Data' button

Before

data is empty string, loading is false

→

After

loading is true, data is empty string; then loading is false, data is set to fetched text

Re-renders:The entire component re-renders to update the loading message and then show fetched data

UI Quiz - 3 Questions

What happens on the screen immediately after pressing the 'Fetch Data' button?

A The text changes to 'Loading...'

B The button disappears

C The title text changes

D Nothing changes

Key Insight

Using the Fetch API in React Native involves triggering a network request on user action, managing loading state, and updating the UI to show feedback. The component re-renders when state changes to reflect loading and data results, providing a smooth user experience.