Beginner's Guide to Javascript

Brendan Eich created JavaScript (JS) in 1995 as a high-level, multi-paradigm programming language that is time-compiled. This language is formally known as ECMAScript.

With 97% of websites using it for client-side scripting, JavaScript is the most used client-side scripting language on the Internet. Javascript is one of three components after HTML and CSS that any web developer should master. It's important to note that Java and Javascript are two separate programming languages.

As a client scripting language, Javascript is one of the most common languages and is needed for web development. Web servers, applications, games, and various mobile applications can be built using this effective programming language. The millennium’s favourite Netflix uses Javascript for its front-end development, while the popular game among Indian mothers, Candy Crush, also uses Javascript among other interesting apps. From displaying animations to showing information in one click, it can be easily done with JavaScript.

Want an introductory session with a professional on the basics of JavaScript? Here is a video for the same!

Building Blocks Of JavaScript

The building blocks of programming languages are their statements, functions, and data types.


A function is a collection of reusable code that can be used at any point in the software. The same code does not need to be rewritten. It facilitates the writing of modular code by programmers. A programmer may use functions to break down a large program into smaller, more manageable functions.

A JavaScript function is a snippet of code that accomplishes a specific goal. The function keyword is followed by a name, then parentheses to define a JavaScript function (). A return statement can be utilised in a JavaScript feature. If you want a feature to return a value, you'll need to do this. In a function, this statement should come last.

Javascript Variables

Anything that varies is referred to as a variable. Data can be placed in these containers and then be referred to by simply naming the container. Local variables and global variables are two different types of variables in JavaScript.

A local variable in JavaScript is declared inside a block or method. It can only be accessed from within the feature or block. Any function in JavaScript can be accessed as a global variable.

In JS, declaring a variable is done with the var statement.

Watch the video below for demonstrations of declaring a function and variable!

Conditional Statements

Conditional statements are used in JavaScript to monitor actions and decide whether or not the code will run.

In JavaScript, there are several different types of conditionals, including:

“If” statements: When a condition is true, it is used to signify that a block of code should be executed.

“Else” statements: The execution of a block of code is defined when the same condition is incorrect.

“Else if” statements: If the first condition is incorrect, this determines a new test.

Switch: It can be used to define a variety of different code blocks to run.

Loops in JavaScript

Looping is a feature in programming languages that allows a set of instructions/functions to be repeated until some condition evaluates to true.

Types of Loop

  1. Entry Controlled Loops: An entry controlled loop is any loop in which we verify the test condition before entering it. The test condition in these loops decides whether or not the program enters the loop. For example, while, for, and so on.

  2. Exit Controlled Loops: An exit controlled loop is one in which the test condition is checked after each statement has been executed. The test condition specifies whether the program will exit the loop or not in these loops. Doing...while loop falls under this category.

While loop

A while loop is a control flow statement that permits code to be performed repeatedly if a Boolean condition is met. The while loop is similar to an if statement that repeats itself.

For Loop

Loops in JavaScript are similar to loops in Java and C. It's an entry-controlled loop. It has three components, each separated by a semicolon: initialization, condition, and increment/decrement in one line, resulting in a looping structure that is shorter and easier to debug.

For… In Loop

The loop makes it easier to iterate over an object's properties. This implies that for each distinct property in a JavaScript Object, the loop executes a particular collection of statements. The the loop was developed by the developers in order to work with user-defined properties in an object.

Do While Loop

The do-while loop is identical to the while loop, with the exception that it checks for the condition after executing the statements, making it an Exit example. The condition is tested for a true or false value after the statements have been run and the variable value has been modified. The next iteration of the loop begins if it is checked to be true. The JavaScript interpreter exits the loop if it returns false.

Data Types

A data type is an attribute of data in programming languages that informs the compiler or interpreter how the programmer plans to use the data. In JavaScript, there are mainly two types of data types.

  • Primitive Data Type

A primitive data value is a single basic data value that does not have any additional properties or methods. It consists of the data types mentioned below.

  1. String: Textual data is represented using the string data type.

  2. Number: As the name suggests, it is used for representing numerical data.

  3. Boolean: True or false are the two possible values for this data type.

  4. Undefined: It is a data type with an uninitialized variable.

  5. Null: A data form with no value is denoted by null.

  • Non-Primitive Data Type

This data type can store both simple and complex entities.

  1. Object: In the form of "key: value" pairs, an unordered set of related data of primitive or reference forms is called an object. In the context of an object, these keys may be variables or functions, and they are referred to as properties and methods, respectively.

  2. Array: An array can contain several values under a single name, and the values can be accessed by referring to an index number.

  3. RegExp: The RegExp object is used to find text that matches a sequence.