JavaScript

🔒 Scope, hoisting and closures

Who can see which variable, why something sometimes exists before you declare it, and how a function remembers the world where it was born.

What you'll learn

• Distinguish global, local and block scope, and predict from where a variable is accessible.
• Explain the hoisting of declared functions and the temporal dead zone (TDZ) of let and const.
• Create a closure that keeps private state between calls, like a counter.
• Implement a function factory by taking advantage of the fact that each closure remembers its own environment.

Lessons