A higher-order function is a function that can take another function as an argument, or that returns a function as a result.

A Higher-Order function is a function that receives a function as an argument or returns the function as output.

let total = 0, count = 1;

while (count <= 10) {

total += count;

count += 1;

}

console.log(total);

console.log(sum(range(1, 10)));

it is using below high order functions like .filter(), .map() and .reduce()

Let’s say we have an array of numbers and we want to create a new array which contains double of each value of the first array.

Without Higher-order function

const arr1 = [1, 2, 3];

const arr2 = [];

for(let i = 0; i < arr1.length; i++) {

arr2.push(arr1[i] * 2);

}

// prints [ 2, 4, 6 ]

console.log(arr2);

With Higher-order function map

const arr1 = [1, 2, 3];

const arr2 = arr1.map(function(item) {

return item * 2;

});

console.log(arr2);

The filter() method creates a new array with all elements that pass the test provided by the callback function.

const persons = [

{ name: 'Peter', age: 16 },

{ name: 'Mark', age: 18 },

{ name: 'John', age: 27 },

{ name: 'Jane', age: 14 },

{ name: 'Tony', age: 24},

];

const fullAge = [];

for(let i = 0; i < persons.length; i++) {

if(persons[i].age >= 18) {

fullAge.push(persons[i]);

}

}

console.log(fullAge);

With Higher-order function filter

const persons = [

{ name: 'Peter', age: 16 },

{ name: 'Mark', age: 18 },

{ name: 'John', age: 27 },

{ name: 'Jane', age: 14 },

{ name: 'Tony', age: 24},

];

const fullAge = persons.filter(person => person.age >= 18);

console.log(fullAge);

The reduce method executes the callback function on each member of the calling array which results in a single output value.

With Higher-order function reduce

const arr = [5, 7, 1, 8, 4];

const sum = arr.reduce(function(accumulator, currentValue) {

return accumulator + currentValue;

});

// prints 25

console.log(sum);

Without Higher-order function

const arr = [5, 7, 1, 8, 4];

let sum = 0;

for(let i = 0; i < arr.length; i++) {

sum = sum + arr[i];

}

// prints 25

console.log(sum);