🔍 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?
- Closures are useful when you want to:
- Preserve state across function calls
- Encapsulate variables (data hiding / private variables)
- Create function factories
- 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
Top comments (5)
Interesting to read
Closures are my go-to for stateful patterns, especially in React hooks. What's your favorite closure use case outside of React?
Yes a favorite closure use case outside React: data privacy in JavaScript modules — like creating private counters or configs without exposing variables globally.
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