High-Order Array Methods

High-order array methods in JavaScript, including map(), filter(), and reduce(), provide powerful tools to efficiently manipulate and process arrays, enhancing code readability and simplicity.

Map() method

It applies a given function on all the elements of the array and returns the updated array. It is the simpler and shorter code instead of a loop. The map is similar to the following code:

Syntax

array.map(callback(element, index, array))

Let's understand this with the help of example:

function triple(n){
    return n*3;
}    
arr = new Array(1, 2, 3, 6, 5, 4);

var new_arr = arr.map(triple)
console.log(new_arr);

Output: 
[ 3, 6, 9, 18, 15, 12 ]

Reduce() method

It reduces all the elements of the array to a single value by repeatedly applying a function. It is an alternative of using a loop and updating the result for every scanned element. Reduce can be used in place of the following code:

Syntax

array.reduce(callback(accumulator, element, index, array), initialValue)

Let's understand this with the help of example

function product(a, b){
    return a * b;
}
arr = new Array(1, 2, 3, 6, 5, 4);

var product_of_arr = arr.reduce(product)
console.log(product_of_arr)

Output:

720

Filter() method

Filter method filters the elements of the array that return false for the applied condition and returns the array which contains elements that satisfy the applied condition.

Syntax:

array.filter(callback(element, index, array))

Let's understand this with the help of example

arr = new Array(1, 2, 3, 6, 5, 4);
var new_arr = arr.filter(function (x){
    return x % 2==0;
});

console.log(new_arr)

Output:

[ 2, 6, 4 ]