What are Closures?
A closure is a fundamental concept in JavaScript that allows a function to access variables from its outer (enclosing) scope even after the outer function has finished executing.
How Closures Work
When a function is defined inside another function, it has access to:
- Its own local variables
- Variables from the outer function
- Global variables
Practical Examples
Closures are commonly used for:
- Data privacy and encapsulation
- Creating function factories
- Implementing callbacks and event handlers
- Module patterns
"Closures are a way to let a function have 'private' variables. The counter is protected by the scope of the anonymous function, and can only be changed using the add function."
Understanding closures is crucial for writing effective JavaScript code and is a key concept that separates intermediate developers from advanced ones.