In what cases can a function be used?

• When it is necessary to reuse a block of code without duplication.
• For structuring a program by dividing it into logical parts.
• To encapsulate logic, hiding implementation details.
• When working with asynchronous operations or events (e.g., callbacks).
• To create closures that retain access to variables from an outer scope.
• When defining methods of objects or classes.
• For data processing, for example, in array methods (map, filter, reduce).

// Reuse
function greet(name) {
  console.log(`Hello, ${name}!`);
}

greet('World');
greet('User');

// Callback for asynchronous operation
setTimeout(function() {
  console.log('Executed after 1 second');
}, 1000);