Head of Array

Introduction

In this lab, we will explore a JavaScript function that returns the head of an array. The function checks if the input array is valid and returns the first element if it exists, otherwise it returns undefined. Through this lab, you will gain a better understanding of array manipulation in JavaScript and learn how to handle edge cases when working with arrays.

Skills Graph

How to Get the First Element of an Array in JavaScript

To get the first element of an array in JavaScript, you can use the head function. Here's how you can use it:

1. Open the Terminal/SSH.
2. Type node to start practicing coding.
3. Use the following code to get the head of an array:

const head = (arr) => (arr && arr.length ? arr[0] : undefined);

4. Call the head function with an array as its argument to get the first element. If the array is empty or falsy, the function will return undefined.

Here are some examples:

head([1, 2, 3]); // 1
head([]); // undefined
head(null); // undefined
head(undefined); // undefined

Summary

Congratulations! You have completed the Head of Array lab. You can practice more labs in LabEx to improve your skills.