JavaScript Closures Explained with Examples

Short summary

Closures are functions that retain access to variables from their definition scope even after execution ends. Essential in JavaScript for encapsulation, event handlers, and React hooks. Understanding lexical scope—where a function is written determines what it can access—is the foundation.

• •Closures let functions carry a 'backpack' of variables from their birth environment indefinitely, enabling private variables and stateful factories
• •React hooks, event listeners, and module patterns all depend on closures—a critical pattern for modern AI product development
• •The core rule: a function accesses variables based on where it's defined, not where it's called; the engine keeps captured variables alive as long as the function references them

Generated with AI, which can make mistakes.