Feature Toggling Middleware

Demonstrate the use of middleware to enable or disable features dynamically without redeploying the app.

const express = require('express');
const app = express();
const PORT = 3000;

// Feature toggles object simulating a dynamic store or config
const featureToggles = {
    newFeature: true
};

// Middleware to check feature toggle
const featureToggleMiddleware = (req, res, next) => {
    const featureName = req.query.featureName;
    if (featureToggles[featureName]) {
        next();
    } else {
        res.status(403).send('Feature is disabled');
    }
};

This code sets up an Express application and a feature toggle configuration. It defines the featureToggleMiddleware which will check if a feature is enabled based on query parameter before proceeding with the request.

app.use((req, res, next) => {
    console.log(`Request received: ${req.method} ${req.url}`);
    next();
});

// Applying the feature toggle middleware globally, it affects all routes
app.use(featureToggleMiddleware);

This code snippet demonstrates how to use middleware for logging requests and applies the featureToggleMiddleware globally to the Express application.

app.get('/new-feature', (req, res) => {
    res.send('New feature is accessible because the toggle is enabled.');
});

app.listen(PORT, () => {
    console.log(`Server running on port ${PORT}`);
});

Here we define a route that would be affected by the featureToggleMiddleware. The app listens on the specified PORT, and the response is sent only if the feature toggle for 'new-feature' is enabled.