JavaScript higher-order functions

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JavaScript Higher-Order Functions

JavaScript higher-order functions are functions that can take other functions as arguments or return functions as results. They enable you to write concise and reusable code, and promote functional programming practices.

What is a Higher-Order Function?

A higher-order function is a function that can accept other functions as arguments or return functions as results. It allows you to abstract and encapsulate behavior, making your code modular.

JavaScript Higher-Order Functions Examples

Here's an example that demonstrates the use of higher-order functions:

const numbers = [1, 2, 3, 4, 5];
const doubled = numbers.map((num) => num * 2);

In this example, the map() function is a higher-order function that accepts a callback function as an argument. It applies the callback function to each element in the numbers array and returns a new array with the results.

JavaScript Higher-Order Functions Exercises

Here's an exercise you can try:

// Write a higher-order function that filters even numbers from an array
function filterEvenNumbers(numbers) {
  return numbers.filter((num) => num % 2 === 0);
}

Hint: The filterEvenNumbers() function is a higher-order function that accepts an array as an argument and returns a new array that contains only the even numbers from the original array. The callback function is used to determine whether a number is even. If the number is even, the callback function returns true, and the number is included in the new array. Otherwise, the callback function returns false, and the number is not included in the new array.

JavaScript Higher-Order Functions Interview Questions

1. What are higher-order functions in JavaScript?
2. How do you pass a function as an argument in JavaScript?
3. What are the benefits of using higher-order functions?

JavaScript Higher-Order Functions Cheat Sheet

- Higher-order functions can accept functions as arguments or return functions as results.
- Common higher-order functions in JavaScript include map, filter, reduce, and forEach.
- Callback functions are often used as arguments for higher-order functions.
- Higher-order functions enable code reusability and promote functional programming practices.

What are Higher-Order Functions vs First-Class Functions in JavaScript?

Higher-order functions and first-class functions are closely related concepts. In JavaScript, all functions are first-class functions, which means they can be treated as values and assigned to variables. Higher-order functions, on the other hand, specifically refer to functions that can manipulate or operate on other functions.

FAQ (Interview Questions and Answers)

1. What are higher-order functions in JavaScript?
   Higher-order functions are functions that can accept other functions as arguments or return functions as results.
   Higher-order functions are functions that only accept numbers as arguments.
   Higher-order functions are functions that cannot be assigned to variables.
   
2. How do you pass a function as an argument in JavaScript?
   You can pass a function as an argument in JavaScript by simply using the function name without invoking it.
   You cannot pass a function as an argument in JavaScript.
   You need to convert the function into a string to pass it as an argument.
   
3. What are the benefits of using higher-order functions?
   Using higher-order functions promotes code reusability, enables functional composition, and allows for cleaner code.
   Higher-order functions make the code more complex and harder to understand.
   Higher-order functions can only be used in specific programming paradigms.
   

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