JavaScript in Detail: From Beginner to Advanced/

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Array Methods

Array Methods

Introduction to array methods that use functions.

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In this lesson, we’ll discuss array methods and their convenient usages.

Introduction

Methods of an object are property names assigned to functions. These methods can be invoked to execute the function. Now, let’s take a look at different methods.

forEach method

forEach method is used to iterate an array in loops. Let’s dig deeper into this method.

Syntax of forEach method

The syntax of the forEach method is as follows.

arr.forEach(<function>);

The forEach method above takes, as an argument, a function invoked for each element in the array. The function to be passed is given arguments in the following order, by the forEach method.

function callbackfn(value: any, index: number, array: any[])

For each element, the callbackfn is passed with the value of the element as the first argument, followed by the index of the element as the second argument, and lastly the array itself as the third argument. We may write the callbackfn function to take 0 to 3 arguments.

Look at a couple of examples.

Node.js
var arr = [10, 20, 30, 40, 50]; // initialise an array and assign to arr
arr.forEach((val, ind, array) => { // arrow function to print arguments
    console.log("Value:", val, " Index:", ind, " arr:",array); // print values
    });
console.log(arr); // print array assigned to arr

In the above example, we call the forEach method for the array assigned to arr variable. To the forEach method, we pass an arrow function which takes three arguments: val, ind, ...