Build and Run the Yakult App Mobile Client

The Yakult App mobile client is a React Native application built with Expo and powered by Expo Router for file-based tab navigation. It communicates exclusively with the Express.js backend over HTTP, so the backend server must be running and reachable from your device or emulator before you launch the app. The steps below cover everything from installing dependencies to picking your run target.

Prerequisites

Node.js 18+ — nodejs.org
Expo CLI — install globally with npm install -g expo-cli
Android Studio (for Android emulator) or Xcode (for iOS simulator) if you plan to run native builds
Expo Go app installed on a physical device for quick QR-code testing (Android / iOS)
The backend server running and reachable — see Backend Setup

Setup

Install mobile dependencies

Navigate into the yakult-app directory and install all JavaScript packages.

cd yakult-app && npm install

Configure the backend API URL

Open yakult-app/services/db.ts and update the BASE constant at the top of the file to point to your running backend server.

// Default — works for iOS simulator and web browser
const BASE = 'http://localhost:3000/api';

// Android emulator — emulator maps 10.0.2.2 → host machine's localhost
// const BASE = 'http://10.0.2.2:3000/api';

// Physical device — use your machine's LAN IP address
// const BASE = 'http://192.168.1.X:3000/api';

The file ships with http://localhost:3000/api active. Change BASE to the line that matches your target and comment out the others.

Target	`BASE` value
iOS simulator / web browser (default)	`http://localhost:3000/api`
Android emulator	`http://10.0.2.2:3000/api`
Physical device (Android or iOS)	`http://<your-LAN-IP>:3000/api`

To find your LAN IP address:

Windows: run ipconfig in Command Prompt — look for IPv4 Address under your active adapter
macOS / Linux: run ifconfig in Terminal — look for inet under en0 or your active interface

The mobile app and your backend server must be on the same local network when using a physical device. If the app cannot reach the API it will time out silently on login or data-fetch screens.

Start the Expo development server

Launch the Expo Metro bundler from the yakult-app directory.

npx expo start

The terminal will display a QR code and a menu of keyboard shortcuts for selecting your run target.

Install Expo Go on your physical Android or iOS device and scan the QR code shown in the terminal. This gives you instant hot-reload without needing to install Android Studio or Xcode, and is the fastest way to test on real hardware.

Choose a run target

After npx expo start is running, press one of the following keys in the terminal to open the app on your chosen target:

Key	Action
`a`	Open on Android emulator (requires Android Studio)
`i`	Open on iOS simulator (requires Xcode, macOS only)
`w`	Open in a web browser
Scan QR	Open in Expo Go on a physical device

For a full native build (no Expo Go required), use the dedicated run commands instead:

npx expo start

App structure

The mobile app is organized into a tab-based navigation layout powered by Expo Router. The available screens are:

Tab	Description
Dashboard	Summary of today’s sales activity and key metrics
Productos	Product catalogue — view and manage Yakult product lines
Clientes	Client directory — manage distributor customers
Órdenes	Create and track sales orders
Reportes	Sales reports and export tools
Admin	Master-level administration panel (visible to admin users only)
Perfil	User profile and session management

Setup

Documentation Index

​Prerequisites

​Setup

​App structure

Build docs developers (and LLMs) love

Prerequisites

Setup

App structure