What are Higher-order functions?
One of the main benefits of high-order functions is that they allow for code reuse. By passing a function as an argument to another function, we can use the same function in multiple places, without having to copy and paste the code. Additionally, by returning a function, we can create reusable, composable building blocks that can be used to create complex behaviors.
Another benefit of high-order functions is that they can help to improve the readability of code. By breaking down complex behaviors into small, simple functions, it becomes much easier to understand what the code is doing. Additionally, by using high-order functions, it is possible to write more declarative code, which describes what the code should do, rather than how it should do it.
The Array.prototype.map() function takes a callback function as its argument, and applies it to each element in an array, returning a new array with the results. For example, the following code doubles each element in an array:
const numbers = [1, 2, 3, 4]; const double = x => x * 2; const doubledNumbers = numbers.map(double); console.log(doubledNumbers); // [2, 4, 6, 8]
The Array.prototype.filter() function also takes a callback function as its argument, but only includes elements in the new array for which the callback function returns true. For example, the following code filters out all odd numbers from an array:
const numbers = [1, 2, 3, 4]; const even = x => x % 2 === 0; const evenNumbers = numbers.filter(even); console.log(evenNumbers); // [2, 4]
The Array.prototype.reduce() function takes a callback function and an initial value as arguments, and applies the callback function to each element in the array in order to reduce the array to a single value. For example, the following code calculates the sum of all elements in an array:
const numbers = [1, 2, 3, 4]; const add = (a, b) => a + b; const sum = numbers.reduce(add, 0); console.log(sum); // 10
Cheers to better composition! 🙂