JavaScript Courses

JavaScript is a lightweight, robust programming and scripting language executed on a web browser, and it is easy to learn.

1. JavaScript Data Types

Data Types are fundamental to any programming language.

JavaScript can change the content of HTML. It allows three primitive types of data types to work with.

• Boolean(Boolean value true or false)
• Numbers (Numerical value)
• Strings (contain Characters)

JavaScript also defines NULL (represents no value ) and Undefined (represents undefined value), which define a single value.

It also supports a non-primitive data type known as Object (through which one can access members), Array (Collection of similar values), and RegExp (Regular expression), which is a composite data type. All numbers are defined as floating-point numbers using a 64-bit floating-point format in JavaScript. In JavaScript, it does not make a distinction between integers and floating-point numbers.

2. JavaScript Variables

JavaScript also has variables like other programming languages. Variables can be taken as names of storage locations. It has two variable types (i.e., Local Variable and Global Variable).

Note: In JS, a and A are different variables, Because JS(JavaScript) variables are case sensitive.

Before using any variable, we must declare it first and the rules for declaring variables in JS, also called Identifiers.

Name: It starts with a to z (or) A to Z, Underscores (_), or ‘$’ sign.

After the first letter, we use Digits (0 to 9).

JS(JavaScript)Variables are declared with the var keyword.

For example, correct declaration of variables.

var a=10;

var _name=”Aasha”;

Incorrect declaration of Variables.

var 56=30;

var *xx=120;

We can also declare multiple variables with “var” keywords.

var name,money;

Example 2:

<script>

var k=5;

var l=4;

var z=k+l;

document.write(z);

</script>

—> Output : 9

JavaScript Local Variables

• It is declared and accessible within a function or block. Function parameters are local to the function.
• If we declare the same name for a local and global variable. So, you can hide the global variable.

Example:

<script>

function abc(){

var k=10; // local variable

}

</script>

Example:

<script>

if (20<26){

var a=20; // JS local variable

}

</script>

JavaScript Global Variables

• It is declared and accessible from any function (outside the function) or outside a block with a window object called Global variable.

Example:

<script>

var x=100 ; // declared global variable

function xyz(){

document.writeln(x);

}

function abc(){

document.writeln(x);

}

xyz(); //calling JavaScript function

abc(); //calling JavaScript function

</script>

3. JS (JavaScript) Constant

Constants in JS are defined as “const”. The term ‘const’ does not define any constant value. Instead, it defines a constant reference to a value.

• JS (JavaScript), the ‘const’ variable must be assigned a value when declared. Use ‘const’ while declaring Object, Array, RegExp, and Function.
• Variables defined with ‘const’ cannot be redeclared and reassigned, and these are Block-scoped.
• Variables defined with ‘const’ can change the elements of a constant array and the properties of constant objects.

Example:

// const variable cannot be reassigned.

const x=1.234567;

x=1.23; // give an error

x=x+1; // give an error

// const variable must be assigned.

const x= 1.234567; // correctly assigned

// const variable must be assigned.

const x;

x=1.234567; //incorrectly assigned.

4.JS (JavaScript) Strings

JS Strings is a set of characters or sequence of characters used for storing and manipulating text or characters.

There are two ways to make strings in JS.

• String literal (Using Double quotes)

// var string_name=”My name is Thanos”;

• String Object (Using new keyword)

var string_name=new String(‘My name is Thanos”);

// new used to create an instance.

5.JavaScript String Methods

JavaScript String Methods help us to work with strings. JS treats primitive values as objects when executing methods of JS String.

• JS String charAt(index) Method: Returns the character at the given index.

Example:

<script>

var string=”helloworld”;

document.write(string.char(5));

</script>

Output: o

• JS String concat(str) Method: It joins two strings.

Example:

<script>

var string1=”Hello”;

var string2=”world”;

var string3=string1.concat(string2);

document.write(string3);

</script>

Output: ‘Hello world’

• JS String indexOf(str)Method: It Returns index values of given strings

Example:

<script>

var string=”hello world is my first printing string”;

var s1=string.indexOf(“world”);

document.write(s1);

</script>

Output: 6

• JS String lastIndexOf(str)Method: It returns the last index position of the string.

Example:

<script>

var string=”hello world index”;

var s1=string.lastIndexOf(“world”);

document.write(s1);

</script>

Output: 11

• JS String toLowerCase()Method: It returns a string in lowercase.

Example:

<script>

var string=”HELLO WORLD INDEX”;

var s1=string.toLowerCase();

document.write(s1);

</script>

Output: hello world index

• JS String to LowerCase() Method: It returns a string in uppercase.

Example:

<script>

var string=”hello world index”;

var s1=string.toUpperCase();

document.write(s1);

</script>

Output: HELLO WORLD INDEX

• JS String slice (beginIndex, endIndex) Method: It extracts a part of the given string from the starting index to the last index.

The starting index is inclusive, and the end index is exclusive.

Example:

<script>

var string=”helloworldindex”;

var s1=string.slice(5,8);

document.write(s1);

</script>

Output: two // 8th position is exclusive

• JS String trim() Method: It removes the trailing and leading black spaces from both sides of the string.

Example:

<script>

var string=” helloworldindex ”;

var s1=string.trim();

document.write(s1);

</script>

Output: ‘helloworldindex’

• JS String split() Method: It splits the string with blank spaces.

Example:

<script>

var string=”helloworldindex”;

document.write(string.split(“ ”));

</script>

Output: hello world index

6. JS(JavaScript) Numbers

It returns a numerical value, which can be decimal or without the decimal, may be an integer or floating-point.

Example 1 :

// Creating Number object in JS

var s1= new Number(value);

Example 2:

var a=12; //Integer Value

var a=12.456; // floating point

var c=1e12; // Exponent Value

var d=new Number(10); // integer value using Number object

Output: 12 12.456,1000000000000,10

7. Arithmetic Operators

It operates on two numbers, which can be literals, variables, or expressions.

E.g, +,-,*,/,**(exponentiation),%(modulus),++(increment),--(decrement).

Example:

Let a =10+12; //literal

Let c= a+b; //variables

Let c=(a+b)*10; // Expression

• Increment operator: It increments the number by 1. For example,

<script>

let x = 21;

x++;

let z = x;

document.getElementById("demo").innerHTML = z;

</script>

//the output will be 22

• Decrement operator: It decrements number by 1. For example,

<script>

let x = 21;

x++;

let z = x;

document.getElementById("demo").innerHTML = z;

</script>

//the output will be 20

8.JS Assignment Operators: It assigns the value to a JavaScript variable.

Example :

=,+=,-=,*=,/=,%=,<<=,>>=,>>>=,&=,^=,|=,**=.

The assignment operator(=): It assigns values to variables.

Example: let a=10;

JavaScript Number Objects

The JavaScript number is used to represent numeric values. The value can be an integer or a floating point. JavaScript follows IEEE standards to represent floating-point numbers.

You can create a number object using the Number () constructor. Here is an example,

var n = new Number(value);

To check if the value is a number, you can use the function NaN(). If the value cannot be converted into a number, the above command returns NaN, i.e., not a number.

To assign a number to a variable, you can follow,

var a = 7; //integer value

var b = 34.7;//floating point value

var c = 7e4;//exponent value, it returns 70000

var x = new Number(16) ;//integer value by number object

The output of the above commands is as follows:

7 34.7 7000 16

JavaScript Number Constants

Following is the list of JavaScript Number Constants:

MIN_VALUE: It returns the minimum value.

MAX_VALUE: It returns the largest value.

POSITIVE_INFINITY: It returns positive infinity, which is an overflow value.

NEGATIVE_INFINITY: It returns negative infinity, which is an overflow value.

NaN: it represents “not a number”.

JavaScript Number functions:

isInteger(): it checks whether the given value is an integer.

isFinite(): it checks if the given value is a finite number.

parseInt(): it converts the string passed in the function into an integer number.

parseFloat(): it converts the string passed in the function into a floating-point number.

toString(): it returns the given number in the form of a string.

toPrecision(): it returns the string representing several specified precision.

toFixed(): it returns a string which is a number with exact digits after a decimal point.

toExponential(): it returns a string representing an exponential notation of the given number.

A JavaScript string is a sequence of characters. The new keyword creates an instance of the string. It can be created in the following two ways:

1. By string literal

The string literal is created using double quotes. The syntax is as follows:

var stringname = "your value";

2. By string object

This is done using the new keyword. The syntax is as follows:

var stringname = new String("string value") ;

JavaScript String Functions:

• indexOf(): It provides the character's position in the given string.
• lastIndexOf(): It provides the position of the character present in the given string from the last position.
• charAt(): It provides the value of the character present at the index passed.
• charCodeAt(): It offers the Unicode value of a character present at the index specified in the function.
• concat(): It combines two strings and returns it.
• search(): It searches the specified expression passed in the function in the given string and returns its position if it is present.
• replace (): It replaces a string with the specified replacement.
• match(): It searches for the specified expression passed in the function in the given string and returns the expression if it is present.
• slice(): It returns the part of the given string. It allows us to assign positive and negative indices.
• substr(): It returns a part of the given string based on the specified starting position and the length.
• substring(): It fetches the part of the string based on the specified index.
• toLowerCase(): It converts the specified string into lowercase letters.

• toUpperCase(): It converts the specified string into uppercase letters.
• toLocaleLowerCase(): It converts the specified string into lowercase letters based on the host’s current locale.
• toLocaleUpperCase(): It converts the specified string into uppercase letters based on the host’s current locale.
• valueOf(): It returns the primitive value of the string object.
• toString(): It returns a string representing a particular value.

A JavaScript Boolean is an object that returns either of two values: true or false. The default value of a JavaScript boolean object is false. JavaScript boolean objects can also be created by using a Boolean constructor.

Boolean x = new boolean(value);

JavaScript Boolean properties:

constructor: It returns the reference of the Boolean function used to create the boolean object.

prototype: It allows adding the methods and properties in the Boolean prototype.

JavaScript Boolean functions:

• valueOf(): It converts type into Boolean type.
• toString(): It converts boolean into string type.
• toSource(): It returns the source of a boolean object in string form.

A function in JavaScript is a block of codes written to perform a specific task. Functions enable code reusability. You can define a function once and reuse it by invoking it elsewhere. Hence the two main advantages of functions in JavaScript are as follows:

• Writing fewer codes: You need not write the same code repeatedly to perform the same task. You can define a function instead and call it when required.
• Code reusability: The function can be called multiple times within the same program or outside it.

The syntax to declare a function is as follows:

Function function_name(argument1, argument2, argument3, …… argumentN)

{

// code

}

An example of a function declaration is as follows:

function message()

{

alert(“this is my first message”);

}

A function name can have letters, digits, underscore, and dollar($). The parentheses in function declarations contain arguments separated by commas. Arguments are the values received by the function when invoked. The arguments or parameters behave as local variables inside the function. This means that the local variables are recognized only within the function. Outside the function, these variables need to be defined. Hence, variables with the same name can be used outside the function. When a function is executed, local variables are created - they are deleted when the execution is complete.

Calling a function:

The code inside a function is executed when it is called or invoked. The () operator is used to invoke a function. Calling a function without () will return the object and not the function result.

JS(JavaScript) Arrays: Arrays are the collection of similar types of values or elements.

There are three ways to construct an array in JS(JavaScript):

• Array literal

var array_name=[value1, value2, Value3];

• Creating an instance of Array directly
• Using an Array constructor.

Example:

Const class=[”Class1”,”Class2”,”Class3”];

JavaScript(JS) Array Directly (new keyword):

var array_name=new Array();

Example:

<script>

var x;

var class=new Array();

class[0]=”Akash”;

class[1]=”Vishal”;

class[2]=”John”;

for(x=0;x<class.length;x++){

document.write(class[x] +”<br>”);

}

</script>

JavaScript(JS) Array Constructor: By passing an argument in the constructor to create an instance.

Example:

<script>

var i;

var class=new Array(“John”,”Marry”,”Johnson”);

for(i=0;i<class.length;i++){

document.write(class[i] +”<br>”);

}

</script>

CREATING AN ARRAY: Array literal is the simplest way to create an array in JavaScript. For simplicity, execution speed, and readability, we use an array literal for creating an array. Another way of creating an array is by using ”new Array()”.

Syntax:

const name=[“Ramesh”, ”Mohan”, ”Ram”];

• We can also firstly create an array and then provide an element.

Const name=[];

name[0]=”Ram”;

name[1]=”Rahim”;

name[2]=”Raman”;

JavaScript Loop: for, for/in, for/of, while, do/while are used to iterate the piece of code, which we want to run, repeatedly, each time with a different value.

for loop: it iterates through a block of code for a fixed time interval.

Syntax: for(initialization;condition;increment)

{

//code

}

While loop: If the iteration number is not known to us or we have to throw the loop for an infinite number of iterations, then while loop is to be preferred.

Syntax:

while(condition){

Code to be executed

}

DoWhile Loop: It also iterates the elements for an infinite number of times but at least once for a while code has to be executed whether the condition is true or false.

Syntax:

do{

code

}while(condition);

JS For/in loop: It is used to iterate the properties of an object.

Syntax:

for(key in object){ // key is used to access the value

Code to be executed

}

JS For/of loop: It is used to iterate an object's values, which is already iterated.

Syntax:

for(variable of iterable object) // iterable objects are those which have iterable

//properties.

{ // variable can be declared as const, var or let

Code to be executed

}

An object in JavaScript is an entity that has properties and functions. You should not declare strings, numbers, and booleans as objects. The name-value pairs in JavaScript objects are properties.Object properties:

JavaScript objects are containers for named values called properties. The properties of an object can be accessed in two ways:

• objectName.propertyName

• objectName[“propertyName”]

Object methods:

Objects can have methods that can be stored in properties as function definitions. The methods of an object can be accessed as follows:

• objectName.methodName(

The browser creates a Document Object Model every time a web page is loaded. The DOM is a W3C (World Wide Web Consortium) standard. It is a language-neutral interface that allows scripts and programs to dynamically access and update the structure, style, and content of a document.There are three parts of the W3C Dom standard.

• Core DOM
• XML DOM
• HTML DOM

Some of the methods of document objects are as follows:

• getElementById(): It returns the element having the specified id value.
• getElementsByName(): It returns all the elements with the given name value.
• getElementsByTagName(): It returns all the elements with the specified tag name.
• getElementsByClassName(): It returns all the elements with the specified class name.
• write(“string”): This writes the specified string on the document.
• writeIn(“string”): It writes the specified string on the document with a newline character at the end

DOM is a programming interface that connects web pages to scripts. It defines how a document should be structured, styled, and accessed. The DOM represents a document through a logic tree. We use events in JavaScript to provide a dynamic interface to web pages. Events use bubbling propagation by default - from parent to child. Events can either be inline in the code or an external JavaScript file.

Suppose we want to make some changes to the occurrence of any event, like loading a web page, form submission, etc. Some common events are as follows:

1. Window event attributes: These events are triggered related to the window object

• onload: It fires when the page has finished loading.
• onresize: It occurs when the browser window is resized.

2. Mouse events: These interactions are through the mouse.

• onclick: This event occurs when the mouse is clicked on an element.
• onmouseover: This event occurs when the mouse hovers over an element

3. Keyboard events: These even*ts occur on pressing and releasing keys of the keyboard.

• *onkeyup: it fires when the user releases a key.
• *onkeydown: It fires when the user presses a key.

JSON stands for JavaScript Object Notation and is a lightweight format for storing and moving data. It is used when data is sent from the server to a webpage. It uses human-readable text to store and transport data objects. Hence, the primary purpose of JSON is to serialize structured data and exchange it over a network.

JSON was derived from the JavaScript/ECMAScript programming language but is language-independent. The format of JSON is syntactically similar to the JavaScript code for creating objects. Therefore, a JavaScript program can easily convert JSON code to JavaScript objects. The JSON format is text only; therefore, JSON data can be easily sent between computers.

• JavaScript has an in-built function for converting JSON strings into JavaScript objects: JSON.parse();
• JavaScript has an in-built function for converting JavaScript objects into JSON strings: JSON.stringify();

JSON allows storing JavaScript objects as text. It enables us to work with data as JavaScript objects. Hence, complicated parsing and translations are required. JavaScript objects can be sent to a server in pure text form.

JSON syntax:

The syntax of JSON is derived from JavaScript object notation syntax. Therefore, it is a subset of JavaScript syntax. The JSON syntax rules are as follows:

• Data is in the form of key-value pairs.
• Commas separate the data.
• Curly brackets are used to hold objects, whereas square brackets are used to contain array elements.

A name-value pair is written with a field name in double quotes, followed by a colon, and then a value:

“Name”: ” mary”

AJAX or Asynchronous JavaScript and XML can send and receive data in various formats like XML, HTML, JSON, and text files. With the help of AJAX, web applications can send and receive data without disturbing the display and behavior of the pages. It allows web pages to update asynchronously by exchanging data with the web servers. Therefore, it is possible to update parts of a web page without loading the entire page.

How AJAX works:

• When the page is loaded on a button click, an event occurs.
• JavaScript creates an XMLHttpRequest object.
• This XMLHttpRequest object sends a request to a web server.
• The server processes the request and sends back a response.
• JavaScript reads the response.
• It performs the proper action accordingly.

AJAX is the JavaScript implementation of partial server requests. The core of AJAX is the XMLHttpRequest object.

• Create an XMLHttpRequest object. The syntax is as follows:

Variable = new XMLHttpRequest();

• Define a callback function which is a function passed as a parameter to another function.

xttp.onload() = function()

{

//what operations to perform

}

• Send a request to the server. You can use the open() and send() methods of the XMLHttpRequest object.
  xttp.open(“GET”, “info.txt”);
  http.send();

JavaScript is an in-demand programming language and is native to web browsers. JavaScript supports skills like dynamic programming, object-oriented programming, and imperative style of programming. It shares many core concepts and capabilities with other programming languages. Hence, it is perfect for beginners who want to learn other programming languages. JavaScript is the most popular and versatile programming language in the world.

Here are a few reasons why JavaScript is suitable for beginners.

• It is in-built into the browser. It is compatible with most web browsers, and you can readily access and learn it.
• It has a simple, straightforward syntax that is beginner-friendly. It takes less time to learn.
• JavaScript is highly in-demand, so the number of programmers learning and working with JavaScript is increasing.
• It has a vibrant and growing community. There are numerous forums and discussion groups where you can post your doubts and participate in discussions to learn more from experienced developers.
• JavaScript is equipped with many tools to make your job easier.

An Online JavaScript course is better than an offline course because it allows you to take up the lessons at your own pace according to your preferences. You do not need to travel, and you will save your energy and time. It is also highly recommended for working professionals and students due to the flexibility of classes.

Now that you know what you can gain through an online vs. offline Javascript course, here’s an overview of the topics included in a standard Javascript course:

• Javascript: An Introduction and Why you should learn it
• Javascript Fundamentals: Variables and data types
• Javascript Fundamentals: Expressions and operators
• Flow control
• Objects and arrays
• Functions and methods
• Constructor and Inheritance
• Pattern matching with regular expressions
• Javascript in browsers.
• The Document Object Model (DOM)
• How to get input and output
• Asynchronous Javascript
• Handling web page events.
• How to script tables and forms.
• Setting up Git and deployment

JavaScript opens up doors to all sorts of high-paying job opportunities. The US Bureau of Labour and Statistics predicts that developer jobs will increase by 15% in 2024. Full-stack developers will be the most sought-after job profiles in the upcoming years. This job has appeared multiple times on the Forbes list as one of the highest-paying jobs. Full-stack developers should be proficient in all aspects of software development, including user experience, databases, and deployment. Therefore, JavaScript is a must-have tool for understanding front-end and back-end development.

The most popular trends that make JavaScript relevant and in-demand are as follows:

• Artificial Intelligence (AI)

Artificial Intelligence is not an unknown term today. It is already revolutionizing the healthcare and marketing industries. It is an emerging field and will continue to grow bigger soon. This also makes it evident that the job opportunities will grow at the same rate. Full-stack developers proficient in JavaScript are highly paid in the fields of Artificial Intelligence.

• Blockchain

Blockchain is a distributed database that securely stores data. It is widely used in cryptocurrencies, but it has also found its use in identity management, supply chain management, and smart contracts. Full-stack developers can find many job opportunities in this area as many issues must be addressed.

• Low-Code Development

Many low-code platforms let users from no-technical backgrounds or users who are not highly skilled develop websites and applications. These platforms have inbuilt capabilities to select and use features without explicit coding. These platforms give the option of touch and click and create applications.

• Progressive Web Applications

Progressive Web Applications (PWAs) combine the features of mobile, web, and desktop applications into one. Websites built as web apps are getting more popular, and most websites are switching to web app versions. JavaScript is the most popular language for full-stack development in this regard. It can be used with many popular frameworks like Angular and NodeJS.

There are around 400 billion active websites on the internet, and the number keeps increasing. The dependence on the internet increases, and hence the focus on web development also rises. JavaScript helps to add many functionalities to web pages. It facilitates smooth interactions between the user and the websites. There has been a massive rise in frontend technologies.

A JavaScript developer can earn around Rs 3 lakhs per annum at entry-level positions. Many developers start as front-end developers and later transition into full-stack developers. This high-paying job is in great demand in the IT industry.

The number of job opportunities and pay for JavaScript developers are high in tech hubs like Bangalore and Hyderabad. Cities like Mumbai and New Delhi also offer good career opportunities.

The popular companies hiring JavaScript specialists in India are as follows:

• Accenture
• Tata Consultancy Services
• Infosys
• Wipro
• Capgemini
• Cognizant

Many product-based companies and startups may pay higher than service-based companies.

Factors on which JavaScript Specialist Salary in India Depends

The factors on which the JavaScript salary depends are as follows:

• Skillset: The skill set will always hold the highest priority in deciding the salary of a JavaScript specialist in India. An individual must have a strong understanding of all the concepts of JavaScript, like the imperative and dynamic programming styles and object-oriented programming. They should be proficient with coding from beginner to advanced level. Knowledge of frameworks like NodeJS and AngularJs can help you land a high-paying job. Also, skills related to Artificial Intelligence and Machine Learning are helpful.
• Level of Experience: The level of experience is a major deciding factor for salary. The more experience you have, the more compensation you are likely to get. The kind of projects you have worked on in your previous role, and the responsibilities you have taken, also add credibility to your resume.
• Type of Company: There is a big crowd in service-based companies. They hire web developers in large numbers. You can always get good job opportunities in one of these service-based companies like Accenture, Wipro, Infosys, Cognizant, etc. Other than these, product-based startups like Myntra, Ola, Yulu, Oyo, etc., can offer even higher salaries. The number of employees in these companies is not very high, and you get more exposure and learning opportunities in such environments.
• Work Location: In India, cities like Hyderabad and Bangalore offer great job opportunities for JavaScript specialists. These are the tech hubs with some of the top tech companies. Other cities like Mumbai, Kolkata, New Delhi, and Chennai have some companies paying decent salary packages to JavaScript developers.

JavaScript Specialist Starting Salary in India

The starting salary of a JavaScript developer in India is Rs 2 lakhs per annum, which can go up to Rs 15 lakhs per annum, depending on skills and experience. Some of the job roles available are as follows:

• Frontend web developer
• Web applications developer
• Software engineer
• Website administration developer

Javascript specialists are most highly paid in the United States. According to Payscale, the average salary of a Javascript developer in the US is $84,000. This can go up to $118,000 based on the experience levels and skillset. Eastern Europe has also become a popular destination for high-paying Javascript developer jobs.

JavaScript Specialist Starting Salary Abroad

The starting salary of a Javascript developer abroad is $72,000. It is the highest in the United States. In countries like Germany, Switzerland, Norway, Netherlands, etc., the starting salary is $62,000-$68,000 for Javascript specialists.

Factors on which JavaScript Specialist Abroad salary depends

CNBC, Dice, and Infoworld named Javascript one of the easiest to learn and the most in-demand programming languages. It is the most widely popular language according to HackerRank Developer Skills Report 2020. It is a high-paying job, and the salary can go high depending on experience, skillset, company, etc. Some of the deciding factors are as follows:

• Skillset: Javascript frameworks add to the skillset of a candidate. Javascript frameworks like Angular.js, Node.js, Vue.js, etc., are highly in-demand, and you can expect a good salary through these. Instagram, Facebook, WhatsApp, and many tech giants use React.js for web development. Microsoft, Youtube, Google, Apple, etc., use AngularJS for their web development projects.
• Experience: It is one of the critical factors in deciding your salary as a Javascript developer. The average salary for JS developers with an experience of 1-4 years is $85,413. It is $89,891 for professionals with 5-9 years of experience. This rises to $145,645 for an experience of 20 years and above.
• Location: The United States is the highest paying country for Javascript developers. There are many job openings, and tech companies are hiring actively. Eastern European countries also pay well. The average salary of a Javascript developer in Germany is $92,225. In the Netherlands, it is $91,879; in Finland, it is $85,913.