JavaScript: Arrays

Published on : August 13,2022

Hi dev,

In this article we will learn about Arrays in javascript.

In contrast to variables, an array can store multiple values. Each value in an array has an index, and each index has a reference in a memory address. Each value can be accessed by using their indexes. The index of an array starts from zero, and the index of the last element is less by one from the length of the array.

An array is a collection of different data types which are ordered and changeable(modifiable). An array allows storing duplicate elements and different data types. An array can be empty, or it may have different data type values.

Examples

Exercise

Exercise: Level 1

const countries = [
  'Albania',
  'Bolivia',
  'Canada',
  'Denmark',
  'Ethiopia',
  'Finland',
  'Germany',
  'Hungary',
  'Ireland',
  'Japan',
  'Kenya',
]

const webTechs = [
  'HTML',
  'CSS',
  'JavaScript',
  'React',
  'Redux',
  'Node',
  'MongoDB',
]

Declare an empty array;
Declare an array with more than 5 number of elements
Find the length of your array
Get the first item, the middle item and the last item of the array
Declare an array called mixedDataTypes, put different data types in the array and find the length of the array. The array size should be greater than 5
Declare an array variable name itCompanies and assign initial values Facebook, Google, Microsoft, Apple, IBM, Oracle and Amazon
Print the array using console.log()
Print the number of companies in the array
Print the first company, middle and last company
Print out each company
Change each company name to uppercase one by one and print them out
Print the array like as a sentence: Facebook, Google, Microsoft, Apple, IBM,Oracle and Amazon are big IT companies.
Check if a certain company exists in the itCompanies array. If it exist return the company else return a company is not found
Filter out companies which have more than one 'o' without the filter method
Sort the array using sort() method
Reverse the array using reverse() method
Slice out the first 3 companies from the array
Slice out the last 3 companies from the array
Slice out the middle IT company or companies from the array
Remove the first IT company from the array
Remove the middle IT company or companies from the array
Remove the last IT company from the array
Remove all IT companies

Exercise: Level 2

1. Create a separate countries.js file and store the countries array into this file, create a separate file web_techs.js and store the webTechs array into this file. Access both file in main.js file

2. First remove all the punctuations and change the string to array and count the number of words in the array

let text =
  'I love teaching and empowering people. I teach HTML, CSS, JS, React, Python.'
console.log(words)
console.log(words.length)

["I", "love", "teaching", "and", "empowering", "people", "I", "teach", "HTML", "CSS", "JS", "React", "Python"]

13

3. In the following shopping cart add, remove, edit items

const shoppingCart = ['Milk', 'Coffee', 'Tea', 'Honey']

add 'Meat' in the beginning of your shopping cart if it has not been already added
add Sugar at the end of you shopping cart if it has not been already added
remove 'Honey' if you are allergic to honey
modify Tea to 'Green Tea'

4. In countries array check if 'Ethiopia' exists in the array if it exists print 'ETHIOPIA'. If it does not exist add to the countries list.

5. In the webTechs array check if Sass exists in the array and if it exists print 'Sass is a CSS preprocess'. If it does not exist add Sass to the array and print the array.

6. Concatenate the following two variables and store it in a fullStack variable.

const frontEnd = ['HTML', 'CSS', 'JS', 'React', 'Redux']
const backEnd = ['Node', 'Express', 'MongoDB']

console.log(fullStack)

["HTML", "CSS", "JS", "React", "Redux", "Node", "Express", "MongoDB"]

Exercise: Level 3

1. The following is an array of 10 students ages: js const ages = [19, 22, 19, 24, 20, 25, 26, 24, 25, 24] - Sort the array and find the min and max age - Find the median age(one middle item or two middle items divided by two) - Find the average age(all items divided by number of items) - Find the range of the ages(max minus min) - Compare the value of (min - average) and (max - average), use abs() method

1.Slice the first ten countries from the countries array

2. Find the middle country(ies) in the countries array

3. Divide the countries array into two equal arrays if it is even. If countries array is not even , one more country for the first half.

Hope it can help you…

Categories : JavaScript

Tags : JavaScript

Praful Sangani

I'm a passionate full-stack developer with expertise in PHP, Laravel, Angular, React Js, Vue, Node, Javascript, JQuery, Codeigniter, and Bootstrap. I enjoy sharing my knowledge by writing tutorials and providing tips to others in the industry. I prioritize consistency and hard work, and I always aim to improve my skills to keep up with the latest advancements. As the owner of Open Code Solution, I'm committed to providing high-quality services to help clients achieve their business goals.