A higher-order function is a function that either takes one or more functions as arguments or Returns a function as its result. These functions are a key concept in functional programming and allow for more abstract, reusable, and modular code.

Example of a Higher-Order Function

Function that takes another function as an argument:

function greet(name) { return `Hello, ${name}`; } function logGreeting(fn, name) { console.log(fn(name)); } logGreeting(greet, 'John'); // Hello, John 

n this example, logGreeting is a higher-order function because it accepts another function (greet) as an argument.

Function that returns another function:

function multiplyBy(factor) { return function(number) { return number * factor; }; } const double = multiplyBy(2); console.log(double(5)); // 10 

Here, multiplyBy is a higher-order function because it returns a new function that multiplies a number by the specified factor.

We can see there are some built-in Higher-Order Functions in JavaScript. Some of them are:

1. map()

2. filter()

3. reduce()

4. forEach()

5. every()