Building and deploying web applications has changed a lot over the years. In the past, teams would wait for weeks or even months to release new features. But today, companies want to release updates often sometimes many times a day. This idea is called continuous delivery.
However, not all applications are built the same way. Many older or larger projects are built as monolithic frontends. These are big applications where everything is packed together in one large codebase. Changing one part can affect many others. So how can developers release changes more often without breaking the entire app?
The answer is feature toggles. Feature toggles help teams hide or show new features without changing the main code. This allows developers to test, deploy, and release updates faster and more safely, even in monolithic apps.
For anyone learning modern development through full stack developer classes, understanding feature toggles is a key part of building flexible, production-ready applications.
What Are Feature Toggles?
Feature toggles, also called feature flags, are a simple way to control which features are turned on in your application. Think of them like light switches. When a toggle is ON, the feature is visible to users. When it is OFF, the code is still there, but users don’t see it.
Developers use feature toggles to:
- Test new features in production without showing them to all users
- Roll out features slowly (for example, to 10% of users first)
- Turn off broken features quickly without doing a new deployment
- Share a codebase across multiple versions of an app
This is very helpful when working with monolithic frontends where everything is connected. Instead of waiting for the whole app to be perfect, teams can use toggles to release and test small parts step-by-step.
Why Use Feature Toggles in Monolithic Frontends?
Monolithic frontends are common in large or older web applications. They may be built with frameworks like AngularJS, jQuery, or even large React apps where everything is bundled together. Changing one part may require rebuilding the entire app.
Because of this, deploying new features is risky. One small bug can affect the whole system. That’s why many teams are afraid to deploy often.
Feature toggles reduce this risk. They let developers merge and deploy code even when the feature isn’t ready to be used by everyone. This improves team confidence and helps move towards continuous delivery.
Types of Feature Toggles
There are different types of feature toggles based on how they are used.
1. Release Toggles
These are used to control the release of new features. The code is deployed, but the feature is hidden behind a toggle.
Example:
if (featureToggles.newDashboard) {
showNewDashboard();
} else {
showOldDashboard();
}
2. Experiment Toggles
These are used for A/B testing. Users are shown different versions of a feature to test which works better.
3. Ops Toggles
These are used to manage performance or system load. For example, turning off a heavy feature during high traffic times.
4. Permission Toggles
These are used to control who can see a feature like admins only or paying users.
If you’re enrolled in a full stack course, you may come across these types in real project-based lessons that teach you how to handle real-time toggling with role-based access.
How to Add Feature Toggles
Adding feature toggles can be simple or complex depending on your app. Here’s how to do it simply:
Step 1: Create a Toggle File
Make a file that holds all your toggle settings.
// featureToggles.js
export const featureToggles = {
newDashboard: false,
darkMode: true,
};
Step 2: Use Toggles in Your Code
Check the toggle before running the feature’s code.
import { featureToggles } from ‘./featureToggles’;
if (featureToggles.newDashboard) {
renderNewDashboard();
} else {
renderOldDashboard();
}
Step 3: Update Toggles Without Code Changes
In more advanced setups, you can store toggle settings in a database or use a third-party service like:
- LaunchDarkly
- Unleash
- Split.io
These tools allow teams to turn toggles on and off without deploying new code.
Best Practices for Using Feature Toggles
Using toggles can be powerful, but they also bring new challenges. Here are some tips to use them the right way:
Keep Toggle Code Clean
Write clear and simple toggle logic. Don’t overcomplicate it with too many nested if statements.
Remove Old Toggles
Once a feature is fully released, remove the toggle. Leaving old toggles in the code can create confusion and bugs.
Use Naming Standards
Name your toggles clearly so other developers know what they do.
Example: enableBetaSignup is better than toggle1.
Document Toggles
Keep track of who added the toggle, why, and when it should be removed.
Test Both Paths
When a toggle controls a big change, test both the ON and OFF paths to make sure both work correctly.
These are the kinds of best practices often taught in hands-on full stack developer classes to prepare students for real-world team development.
Real-World Example
Let’s say you have a monolithic e-commerce frontend. You want to add a new payment option, but it’s not fully tested yet. Instead of waiting for weeks to finish everything, you can:
- Wrap the new payment code in a toggle
- Deploy it to production
- Turn it ON only for your internal team
- Collect feedback
- Gradually release it to 10%, then 50%, and finally 100% of users
If something goes wrong, just turn the toggle OFF no rollback needed. This makes deployments safer and faster.
When Not to Use Feature Toggles
While toggles are useful, don’t use them for everything. Avoid using toggles:
- For tiny changes that don’t affect users
- When you don’t have a plan to remove the toggle
- If your team won’t maintain them properly
Too many toggles can make code harder to read and test.
Moving Towards Continuous Delivery
With feature toggles in place, your team can release code more often. This is the first big step towards continuous delivery.
In monolithic frontends, continuous delivery is hard because changes can break other parts of the app. But toggles allow you to:
- Deploy unfinished features without risk
- Test features in production safely
- Roll back instantly by switching toggles off
- Reduce pressure on release days
Over time, you’ll be able to deliver updates daily or even hourly, without fear.
In a modern full stack course, these topics are often included in the advanced sections where students learn deployment, testing, and DevOps basics.
Conclusion
Feature toggles are a simple but powerful way to bring continuous delivery to even the most complex monolithic frontend apps. They let developers push code safely, test features in production, and release updates faster.
Whether you’re working in a startup or a large company, learning how to use feature toggles will make you a better and more confident developer. They improve teamwork, reduce risk, and help bring better software to users more often.
If you’re just starting or planning to upgrade your skills, look for full stack developer classes that include feature toggles, DevOps, and continuous delivery practices as part of their training. This knowledge will make you stand out in any team and prepare you for real-world software development.
The future of software is fast, safe, and always improving and with feature toggles, you’ll be ready to lead the way.
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