Beginner LevelExpress JS
How do you mount sub-applications in Express by passing one Express app instance into another?
❓ Interview Prompt: Explain Express sub-apps, mounting express() instances via app.use(), and isolating configuration settings.
In large microservices or multi-tenant setups, you can instantiate multiple completely independent 'express()' application instances and mount them together!
Sub-App Mounting:
Pass a sub-application instance directly into 'app.use("/subpath", subApp)'. Sub-apps maintain their own settings ('app.set()'), middleware stacks, and route engines.
Code Implementation Example
javascript
import express from 'express';
// Sub-App 1: Admin Application
const adminApp = express();
adminApp.get('/', (req, res) => res.send('Admin Dashboard Home'));
// Master Application Gateway
const mainApp = express();
mainApp.use('/admin', adminApp); // Mount admin sub-app onto /admin prefix!
mainApp.listen(3000);💡Mounting an independent sub-app instance onto a master Express gateway.
🎯 Interview Key Takeaway
Mount sub-applications by passing express() instances to app.use("/prefix", subApp) for isolated app configurations.
#Sub-Apps#Architecture#Mounting#Beginner
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