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Discussion on: What the Hell is Closure in JavaScript?

 
royaljain profile image
Royal Jain CodeParrot

Remembers is the keyword here

Every function has access but not every function remembers

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jonrandy profile image
Jon Randy πŸŽ–οΈ • Edited

They do. All functions are the same in this respect.

From MDN:

In JavaScript, closures are created every time a function is created, at function creation time.

Every function has an associated closure, remembering the lexical environment in which it was created.

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royaljain profile image
Royal Jain CodeParrot

No, they don’t. They access the variables again which are in their lexical scope. In Closure, they store the variables and their values. Which is what your diagram signifies - function + state

To check this - just define a global variable console log in a function change the value and try again. New value will be printed meaning it doesn’t remember it accesses.

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jonrandy profile image
Jon Randy πŸŽ–οΈ • Edited

Every function forms a closure with the lexical scope in which it was created. If a variable changes in that lexical scope, it will see the changed value. Make a JS module, export a function that accesses a module level var - this, again, works due to closures. Change the module level var, the change will be reflected. Often when code takes advantage of closures, it does so within the lexical scope of another function, which it still has access to when that function finishes execution. Closures work the same everywhere.

Your example with the global scope just reinforces the point. The global scope is still active and accessible, so vars there can be easily changed.

Variables are not 'stored' in a closure, a closure has references to the function's lexical scope.