What is a Higher-Order function?
A higher order function is a function that operates on other functions. They can either take functions as arguments, or they can return them. In other words, either you pass inn a function or you get a function in return.
A quick example
First I will show you an example where you have an array of numbers. For each of the values, we want to add 1. This is how you would solve this without higher-order functions:
const arr1 = [1, 2, 3, 4, 5];
const arr2 = [];
for (let i = 0; i < arr1.length; i++) {
arr2.push(arr1[i] + 2);
}
// Print the array
console.log(arr2);
// Will return
// [2, 3, 4, 5, 6]This is how you solve it using a higher-order function (map):
const arr1 = [1, 2, 3, 4, 5];
const arr2 = arr1.map(function(item) {
return item + 1;
});
// Print the array
console.log(arr2);
// Will return
// [2, 3, 4, 5, 6]If you want to make it even shorter, you can use the arrow function syntax:
const arr1 = [1, 2, 3, 4, 5];
const arr2 = arr1.map(item => item + 2);
// Print the array
console.log(arr2);
// Will return
// [2, 3, 4, 5, 6]Questions?
If any of this was unclear, feel free to leave me a reply below!