📖 Closures in JavaScript — Unlocking Private Variables

🔍 What is a Closure?

A closure is a function that remembers the variables from its lexical scope even when the function is executed outside of that scope.

In simpler terms:

Closures allow a function to access variables from an outer function, even after that outer function has finished executing.

🔓 Why Use Closures?

1. Closures are useful when you want to:
2. Preserve state across function calls
3. Encapsulate variables (data hiding / private variables)
4. Create function factories
5. Avoid polluting the global scope

💡 Simple Closure Example

🔐 Closures as Private Variables

Let’s create a function that locks variables from the outside world:

🏭 Function Factory with Closures

⚠️ Common Mistake

People often expect each loop iteration to have a fresh value:

🧠 Closure Summary

🎯 Real-World Applications of Closures

Private methods in JavaScript classes

Maintaining state in React hooks like useState

Functional programming patterns

✅ Conclusion

Closures are one of the most powerful and misunderstood features in JavaScript. Mastering them will unlock a whole new level of confidence in writing secure, modular, and elegant code.

✍️ Written By
Chaitanya Chopde

🌟 Inspired By
@devsyncin

Comments

[Dotallio]

Closures are my go-to for stateful patterns, especially in React hooks. What's your favorite closure use case outside of React?

[Chaitanya Chopde]

Yes a favorite closure use case outside React: data privacy in JavaScript modules — like creating private counters or configs without exposing variables globally.