Skip to main content

Existing Code

Feature flags can be seamlessly integrated into existing code to control the release of new features. Here are two examples demonstrating how to introduce feature flags to prevent new code from reaching production without manual intervention.

Example 1: Conditional Rendering in a Web Application​

Let's say you have an existing TypeScript/React component and you want to conditionally render a new feature based on a feature flag.

Step 1: Define the Feature Flag​

First, define a simple feature flag system. This could be an object or a more sophisticated feature flag management system.

interface FeatureFlags {
    [key: string]: boolean;
}

const featureFlags: FeatureFlags = {
    newFeature: false,  // Set to true to enable the feature
};

Step 2: Integrate Feature Flag into Existing Component​

Next, modify the existing component to conditionally render the new feature based on the feature flag.

import React from 'react';

const ExistingComponent: React.FC = () => {
    const isFeatureEnabled = (feature: string): boolean => {
        return featureFlags[feature] || false;
    };

    return (
        <div>
            <h1>Existing Component</h1>
            {isFeatureEnabled('newFeature') && (
                <div>
                    <h2>New Feature</h2>
                    <p>This is the new feature content.</p>
                </div>
            )}
        </div>
    );
};

export default ExistingComponent;

In this example, the new feature will only be rendered if the newFeature flag is set to true.

Example 2: Conditional Logic in a Backend Service​

Consider a scenario where you have a backend service written in TypeScript, and you want to introduce a new feature while ensuring it does not execute in production.

Step 1: Define the Feature Flag​

Define a feature flag in your configuration or environment variables.

// config.ts
export const featureFlags = {
    newFeature: process.env.NEW_FEATURE === 'true',
};

Step 2: Integrate Feature Flag into Existing Service​

Modify the existing service to conditionally execute the new feature based on the feature flag.

import { featureFlags } from './config';

class ExistingService {
    public processRequest(): void {
        console.log('Processing request with existing logic.');

        if (featureFlags.newFeature) {
            this.newFeatureLogic();
        }
    }

    private newFeatureLogic(): void {
        console.log('Executing new feature logic.');
        // New feature implementation
    }
}

// Sample usage
const service = new ExistingService();
service.processRequest();

In this example, the newFeatureLogic method will only be executed if the newFeature flag is set to true.

Conclusion​

By integrating feature flags into existing code, you can control the release of new features and prevent them from reaching production without manual intervention. This approach allows for safe and gradual rollouts, improved testing, and the ability to quickly disable features if issues arise.