What is a higher-order function?

A higher-order function is a function that:

1. Accepts one or more functions as arguments.
2. Returns another function as a result.

Such functions allow abstraction from specific actions, increasing flexibility and reusability of code.

Examples in JavaScript: map, filter, reduce, setTimeout.

// Example of a higher-order function: Function as an argument
function applyOperation(x, y, operation) {
  return operation(x, y);
}

function add(a, b) {
  return a + b;
}

const result = applyOperation(5, 3, add); // Passing function `add` as an argument
console.log(result); // 8

// Example of a higher-order function: Returning a function
function multiplyBy(factor) {
  return function(number) {
    return number * factor;
  };
}

const multiplyByTwo = multiplyBy(2); // Returning a new function
const value = multiplyByTwo(10); // Using the returned function
console.log(value); // 20

Advantages:

• Improves readability and modularity of code.
• Facilitates creation of abstractions.
• Promotes functional programming style.