JavaScript Tutorial – Best JavaScript Comprehensive Guide for Beginners

In this JavaScript Tutorial, we will learn about the basic aspects of JavaScript. Firstly, we will learn what is JavaScript, then, prerequisites to learn JavaScript, its History, advantages, disadvantages, features, variables, data types, how to add scripts to HTML, how to run JavaScript, its tools, applications, memory management in JavaScript and career prospects in JavaScript.

JavaScript Tutorial

1. What is JavaScript?

JavaScript is a scripting language that is created for showing HTML pages live. JavaScript does not require any compilation. It is interpreted language. JavaScript can modify HTML page, write text in it, add or remove tags, change styles etc.

JavaScript code can get to execute on events, mouse clicks, and movements, keyboard input etc. It can send the request to the server and load data without reloading of the page. This technology is often called “AJAX”. JavaScript makes the web pages dynamic.

JavaScript is also used to get and set cookies, ask for data and output messages.

2. Prerequisites to Learn JavaScript

Before starting JavaScript Tutorial, we will discuss the prerequisites before learning it. JavaScript does not require any complex knowledge as such but one should have knowledge of basic programming languages like Java. One should be good at HTML5, CSS3.

Also, before you function the Interact JavaScript API on a website, you must also mention the interactapi.js file on your web pages.

3. JavaScript History

When JavaScript was created, it initially had another name known as “Live Script”. But, Java was so popular at that time so, they decide to name it as “Younger Brother of Java”. And, with the time, JavaScript became the fully independent language with its own specification called ECMA Script and now it has no relation to Java at all.

Today, JavaScript can execute not only in the browser but also on the server. It can run on any device that has a special program called the JavaScript Engine. Now, the browsers also have an Embedded Engine called “JavaScript Virtual Machines”. Now, we will further explore the JavaScript Tutorial and learn the benefits of JavaScript.

4. Advantages of JavaScript

JavaScript capabilities greatly depend on the environment it is running. For example, Node js supports function that allows JavaScript to read/write arbitrary files, perform network request etc.

In- browser, JavaScript can do all that is related to web page manipulation, the web server, and interaction with the user. In browser, JavaScript has different advantages:

  • Adding new HTML to the page, change the existing content, modify styles.
  • React to the user actions, run on mouse clicks, pointer movements, key presses.
  • Send requests through the network to remote servers, download and upload files. It is called AJAX and COMET Technologies.

5. Disadvantages of JavaScript

Now, in the JavaScript Tutorial, we will discuss the limitations of JavaScript.

  • JavaScript abilities limit by the browser window. It doesn’t have access to the OS. Newer browsers also provide such facilities but in a limited and secure way.
  • JavaScript in a single tab can’t modify other tabs/ windows. These are exceptions when two windows came from the same domain.
  • It has some security issues like any JavaScript snippets while appending onto web pages on the client side, for exploiting the user’s system.
  • We cannot use it for Networking Applications as no supports are available.
  • JavaScript render varies. It may render by different layout engines differently. As a result, it also creates interface and functionality, which is not consistent.

6. Unique Features of JavaScript

The features of JavaScript are as follows:

  • JavaScript designs in such a way that it is case – sensitive, object-oriented and dynamically typed.
  • It is platform independent and it can be interpreted.
  • JavaScript is object scripting language giving the user more control over the browser.
  • It also handles date and time.
  • Detects the user browser and OS and is lightweight.
  • JavaScript is scripting language and it is not Java.
  • All statement must terminate with a semicolon in JavaScript
  • Almost all of the JavaScript control statements syntax is similar to the syntax of control statements in C.
  • Lastly, an important part of JavaScript is the ability to create new functions within the script. Declare a function in JavaScript using the function keyword.

7. JavaScript Variables

Now, in the JavaScript Tutorial, we will learn the variables in JavaScript. JavaScript variables are containers for storing data values. The variable name’s first character must be a letter, $, or “_”. The second character is allowed to be digits.

In addition to this, reserved words can’t be variable names like value function, return etc. A variable can consist of a value of any type. Variable declaration, whenever they occur are process before any code gets to execute. Moreover, the scope of a variable that is declared with “var” is its current execution context.


var X=1;
var y = 2;
y= y+x;

8. Data Types Supported by JavaScript

Further, in JavaScript Tutorial, we will discuss six primitive data types supported by JavaScript are Boolean, String, Number, Undefined, Null, Symbol and Object.

i. Boolean

Boolean is true or false. They are often used for conditional languages.

ii. Strings

As in most languages, JavaScript strings are the grouping of characters.


“hello world”
“I like cats”
“testing quotes”

iii. Numbers

The number Datatype covers integers and float. That is the number type can handle number (1,2,3,4) and also the negative number and decimal places. This is also different from many languages that have multiple data types to support different numbers.


var num= 1;
typeof num;
var num= -1;
typeof num;
var num=0.3;
typeof num;

iv. Undefined

For unassigned values – a standalone type that has a single value and that is not define.

v. Null

Null for unknown values – a standalone type that contains a single value null.

vi. Symbol

This is new in ECMA Script 6. Symbols allow for private properties on objects. Before ECMA Script 6, all the properties for an object could be accessed through for, in.


var dog ={ bark : true }
for ( var property in dog ){
If ( dog.hasOwnProperty(property ) ){
Console.log(property); // logs “barks”

vii. Objects

Everything in JavaScript Tutorial, that we didn’t discuss above is an object. So, objects in JavaScript are the most complex datatype.


var cat = { sounds : “meow” }
Var fluffy = new Cat();
Var whiskers = new function();
This.sound = “meow”;

9. How to Add Scripts to HTML Page – JavaScript Tutorial

The script can put anywhere on the page. Most widely it is placed inside the head tag of the document, before the closing of the body tag and you can write entire JavaScript in the separate external source file and you can also provide the link in the HTML page.


JavaScript code inside the head tag of the document.

<meta charset = “utf-8”>
<title> Introduction to Alert</title>
confirm(“ Are you girl”);
prompt(“enter your name”);
<h1> Welcome to JavaScript </h1>

10. How to Run JavaScript

Now in JavaScript Tutorial, we will see the steps to run JavaScript:

i. Click on HTML file.
ii. Open with the web browser.
iii. For JavaScript code inside the head tag, the Alert message will get execute first.
iv. Click on the ok button.
v. Next, it will display “Are you a girl”?.
vi. Press on ok if you are a girl.
vii. After that, it will prompt you to Enter your name.
viii. Then, this head tag execution, body tag will execute.
ix. A message mentioning “Welcome to JavaScript” is shown.



Are you a girl

Enter your name


JavaScript code inside the body:

<meta charset = “utf-8>
<title> introduction to Alert </title>
<h1> Welcome to JavaScript </h1>
alert ( “Welcome”);
confirm(“Are you a girl”);
prompt(“Enter your name”);

When you run JavaScript code inside the body tag, then when you run HTML page using web browser, it will display first Welcome to JavaScript and along with that popups will also display.



Are you a girl

Enter your name


JavaScript code in separate external file

function popup(){
confirm(“ Are you girl”);
prompt(“Enter your name”);

In html.exe file, we have to give the source script file name when we write JavaScript code in a separate file.

<script src=”popup.js”;
<p onclick=” popup()”>
Click Me



Are you a girl

Enter your name

11. JavaScript Tools

The various tools of JavaScript are as below:


It’s a proprietary cross-platform text editor with Python API. Also, it natively supports multiple languages and marks up languages. Plugins can also be intuitive for new functions.

ii. GULP

GULP is basically a task automation tool. It is also easy to use for developers and easy to understand.

iii. NPM

NPM is known as the Node JS Package manager, which is an online repository for publishing projects created on Node JS.


Web – Packs helps you in loading your modules with some dependencies like .js, .css, .html, etc. Web- packs also help as bundlers that bundle your similar kind of files into a single precise file.


ESLINT is a tool for finding an error. It is a pluggable JavaScript linting tool. This tool will also help you find programming errors and it is a must-have tool for newbies JavaScript testers.


JASMINE is a test suite that runs only when JavaScript is there in your browser. It is a fully automated behavior suite. Hence, it provides a testing environment for all kinds of Node.js projects.


BROWSERIFY can only work with the Node.js projects and to make them live into the browsers. It also works well on small modules.

viii. MOCHA

MOCHA is a simple and flexible testing framework in JavaScript. It also offers asynchronous testing and also you can use any assertion libraries with it.


QUINT is installed on NPM which is a JavaScript testing framework. It is a unit testing framework.


CODE ORCHESTRA  is also known as COLT ( Code Orchestra live coding tool). It can be used by any IDE which is beneficial for the user/coder.


Continuous Integration is a development practice tool that allows developers to integrate their code in a shared repository some times in a day


By using TRAVIS CI, you can sync your GITHUB projects, easily. Travis offers more language support then CIRCLE CI and also runs on Linux and Mac OS at the same time.


CODESHIP is a continuous integration tool helps in error finding. The service also offers a variety of powerful setup options.


APPVEYOR is an open source project builder. It works well for GITHUB repositories. The user can also log in to the actual VM.


JENKINS is a continuous integration server or tool that is in Java. The tool is a standalone CI tool with lots of plugins by which you can do anything.

12. JavaScript Applications

There are various uses of JavaScript in the following domains:

i. Web Development

Firstly, JavaScript is the client scripting language which is for creating web pages. This is a standalone language developed in Netscape. Its use is when a web page is to be made dynamic and add special effects like rollover, roll out and many other types of graphics.

Its use is for every website for the reason of validation. In addition to validation, it supports external applications like PDF document, running widgets supporting for web applications etc. JavaScript can also load contents into document whenever the user requires it without even reloading the entire page.

ii. Presentations

JavaScript provides the facility of creating presentations as a website. It gives Reveal JS and Bespoke JS libraries to create a web-based slide deck. Reveal JS design some of the most attractive and interactive decks using HTML.

It also provides Bespoke. JS plugin with a variety of features. Moreover, these include responsive scaling, animated bullet lists, and syntax highlighting for code examples.

iii. Server Applications

Node JS designs on Chrome’s JavaScript runtime for creating fast and scalable network applications. Also, it uses lightweight, efficient and event-driven applications that are to be distributed over the systems with the help of the server. Also, JavaScript is used to handle the HTTP request and generate contents.

iv. Web Servers

A web server creates with the help of Node JS. Also, the benefits of Node JS are that it does not wait for the response of the previous call and is event driven.

v. Games

JavaScript helps in the creation of games. A user can design a stage and it will also provide the display list to its target canvas.

vi. Smartwatch Applications

JavaScript is the most popular language and its use is in all possible devices and applications.

vii. Mobile Applications

JavaScript helps in building mobile applications without web contexts.

viii. Flying Robots

Using JScript Node JS, a user can program a flying robot.

13. Career in JavaScript

Further, in JavaScript Tutorial, we will learn different career prospects in JavaScript. There is a saying in the world of development that “Every Day is the Learning day in web development”.
Also, there is so much scope for a career in JavaScript developers like:

  • By building your own portfolio site, you can also do freelancing projects along with the regular jobs.
  • There is always a high demand for skilled people.
  • Professional experience may sometimes substitute for education.
  • You can also work across all types of industries like finance, insurance, telecommunications.

14. Memory Management of JavaScript

We will further move on to discuss memory management of JavaScript in JavaScript Tutorial. In C, we have low-level memory management primitives like malloc(), free(). Placement of JavaScript value is when things (objects, strings etc) are designed. They are automatically freed when they are not used using garbage collectors.

In JavaScript, memory allocation is along with declarations. Garbage Collectors use is to free up memory. The hardest task is to find when the allocated memory is not in need any longer.

Some high-level languages also embed a piece of software called “Garbage Collector” whose job is to track memory allocation and also used in order to find when a piece of allocated memory is not required any longer and in that case, it will automatically free it.

Now, we come to the end of our JavaScript Tutorial.

15. JavaScript Tutorial – Summary

JavaScript was initially created with browser only language but now it is being used in many other environments as well.

Today, JavaScript has a unique position as the most widely adopted language with full integration with HTML, CSS. JavaScript is used in many applications and with all features in a front end and back end development, it also helps in supporting and creating some of the best applications that can be used worldwide.

You can also study some other programming languages like Python, Ruby, PHP and lastly, you can study a couple of frameworks like Angular.js and Twitter Bootstrap.

Furthermore, if you have any queries or feedbacks related to the JavaScript Tutorial, you can enter in the comment section.

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