What are some examples of lexical scope in JavaScript?

What are some examples of lexical scope in JavaScript?

Lexical scope refers to the visibility of variables in nested functions. For example, in the following code:

function outerFunction() {
    let outerVariable = 'I am outside!';
    function innerFunction() {
        console.log(outerVariable);
    }
    innerFunction();
}
outerFunction();

The innerFunction can access outerVariable because of lexical scoping.

Can you explain how closures relate to lexical scope?

Sure! Closures are functions that remember their lexical scope even when the function is executed outside that scope. For instance:

function makeCounter() {
    let count = 0;
    return function() {
        count++;
        return count;
    };
}
const counter = makeCounter();
console.log(counter()); // 1
console.log(counter()); // 2

Here, the returned function retains access to count.

What happens if I try to access a variable outside its scope?

If you try to access a variable outside its scope, you'll get a ReferenceError. For example:

function testScope() {
    let localVar = 'I am local!';
}
console.log(localVar); // ReferenceError: localVar is not defined

localVar is not accessible outside testScope.

Can you give me a real-world analogy for lexical scope?

Absolutely! Think of lexical scope like a library. The main library (outer function) has sections (inner functions) that can access the books (variables) in the main library. However, if you go to a different library (global scope), you can't access the books from the first library.