What are JavaScript scopes and closures?

What are JavaScript scopes and closures?

JavaScript scope refers to the accessibility of variables in different parts of your code. Closures are functions that remember their outer scope even when executed outside that scope.

Can you give me an example of a closure?

Sure! Here's a simple example:

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

const myClosure = outerFunction();
myClosure(); // Outputs: I am outside!

In this example, innerFunction is a closure that retains access to outerVariable.

What is the difference between var, let, and const in terms of scope?

var is function-scoped, meaning it's accessible within the function it was declared. let and const are block-scoped, meaning they are only accessible within the nearest enclosing block (like an if statement or a loop). const also requires that the variable be assigned a value at the time of declaration.

How do closures help in JavaScript?

Closures allow for data encapsulation and privacy, enabling you to create private variables and functions. They also help in maintaining state in asynchronous programming.