Higher-order functions in JavaScript are functions that either take other functions as arguments, return functions as their result, or both. This concept is a key aspect of functional programming and allows for more abstract and reusable code.

Key Points about Higher-Order Functions:

1.Taking Functions as Arguments: A higher-order function can accept one or more functions as input parameters. This allows for the creation of more flexible and reusable code.

2. Returning Functions: A higher-order function can return a new function. This is often used for creating closures or functions with a preset configuration.

Examples of Higher-Order Functions:

1. map, filter, and reduce:

- These are common higher-order functions in JavaScript.

 javascript
   // Example of map
   const numbers = [1, 2, 3, 4];
   const doubled = numbers.map(num => num * 2); // [2, 4, 6, 8]


   // Example of filter
   const evens = numbers.filter(num => num % 2 === 0); // [2, 4]


   // Example of reduce
   const sum = numbers.reduce((acc, num) => acc + num, 0); // 10

In these examples, map, filter, and reduce are higher-order functions because they take a function as an argument.

2. Function Returning Function:

- Higher-order functions can also return a function.

javascript
   function multiplier(factor) {
       return function(number) {
           return number * factor;
       };
   }


   const double = multiplier(2);
   console.log(double(5)); // 10

Here, multiplier is a higher-order function because it returns a function that multiplies a given number by a specified factor.

Advantages of Higher-Order Functions:

- Code Reusability: Higher-order functions promote reusability by abstracting common patterns.

- Modularity: They help in breaking down complex problems into smaller, manageable functions.

- Functional Composition: You can compose small functions to create more complex functionality.

Higher-order functions are a powerful tool in JavaScript, enabling developers to write more concise, readable, and maintainable code.