What is the scope chain in JavaScript?

What is the scope chain in JavaScript?

The scope chain in JavaScript is a mechanism that determines the accessibility of variables in nested functions. It allows inner functions to access variables from their own scope and from outer scopes.

Can you give me an example of how the scope chain works?

Sure! Consider this code:

function outer() {
    let outerVar = 'I am outside!';
    function inner() {
        console.log(outerVar);
    }
    inner();
}
outer();

In this example, the inner function can access outerVar because of the scope chain.

What happens if I try to access a variable from a different function?

If you try to access a variable from a different function that is not in the scope chain, you'll get a ReferenceError. For example, if inner tried to access a variable defined in another function, it wouldn't be able to.

How does the scope chain relate to closures?

The scope chain is fundamental to closures. A closure is created when a function retains access to its lexical scope, even when the function is executed outside that scope. This means it can remember the variables from its outer function.