What are some examples of function expressions in JavaScript?

What are some examples of function expressions in JavaScript?

Function expressions are functions defined within an expression. Here are a few examples:

1. Anonymous Function Expression:

   const greet = function() {
       console.log('Hello!');
   };
   greet(); // Outputs: Hello!
   

2. Named Function Expression:

   const factorial = function fact(n) {
       return n <= 1 ? 1 : n * fact(n - 1);
   };
   console.log(factorial(5)); // Outputs: 120
   

3. Immediately Invoked Function Expression (IIFE):

   (function() {
       console.log('This runs immediately!');
   })();
   

Would you like to see more examples or explanations?

Can you explain the difference between function expressions and function declarations?

Sure! The main differences are:

1. Syntax: Function declarations use the function keyword followed by the function name, while function expressions can be anonymous or named and are assigned to variables.

2. Hoisting: Function declarations are hoisted, meaning they can be called before they are defined. Function expressions are not hoisted, so they must be defined before they are called.

3. Scope: Function expressions can create closures, while function declarations do not inherently create closures.

Would you like to know more about closures?

Yes, please explain closures in JavaScript.

Closures are a fundamental concept in JavaScript. A closure is created when a function retains access to its lexical scope, even when the function is executed outside that scope. This means that a function can remember the environment in which it was created.

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 has access to outerVariable even after outerFunction has finished executing. Would you like to explore more examples of closures?