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

Component - Fetch API for POST requests

This React Native component shows how to send data to a server using the Fetch API with a POST request. It has a button that, when pressed, sends a simple message to a fake API and shows the response.

Widget Tree

App
├── View
│   ├── Text ("Press the button to send POST request")
│   ├── Button ("Send POST")
│   └── Text (response message)

The root component is App. Inside it is a View container holding three children stacked vertically: a Text widget with instructions, a Button to trigger the POST request, and another Text widget that displays the server response.

Render Trace - 5 Steps

Step 1: App

Step 2: View

Step 3: Text (instruction)

Step 4: Button

Step 5: Text (response)

State Change - Re-render

Trigger:User presses the 'Send POST' button

Before

response message is empty string

→

After

response message updated with server reply text

Re-renders:App component and its children re-render to show new response text

UI Quiz - 3 Questions

What happens when the 'Send POST' button is pressed?

A The app closes

B Nothing happens

C A POST request is sent and the response is shown on screen

D The button disappears

Key Insight

Using the Fetch API with POST requests in React Native involves setting up a button to trigger the request and managing the response with state. This pattern keeps the UI responsive and updates the screen automatically when new data arrives.