Overview

What is JavaScript?

JavaScript is a dynamic computer programming language. It is lightweight and most commonly used as a part of web pages, whose implementations allow client-side script to interact with the user and make dynamic pages. It is an interpreted programming language with object-oriented capabilities.

JavaScript is a single-threaded programming language that we can use for client-side or server-side development. It is a dynamically typed programming language, which means that we don’t care about variable data types while writing the JavaScript code. Also, it contains the control statements, operators, and objects like Array, Math, Data, etc.

JavaScript was first known as LiveScript, but Netscape changed its name to JavaScript, possibly because of the excitement being generated by Java. JavaScript made its first appearance in Netscape 2.0 in 1995 with the name LiveScript. The general-purpose core of the language has been embedded in Netscape and other web browsers.

The ECMA-262 Specification defined a standard version of the core JavaScript language.

JavaScript is a lightweight, interpreted programming language.
Designed for creating network-centric applications.
Complementary to and integrated with Java.
Complementary to and integrated with HTML.
Open and cross-platform

History of JavaScript

JavaScript is developed by Brendan Eich, a computer scientist and programmer at Netscape Communications Corporation. The initial name of the JavaScript was the ‘Mocha’. After that, it changed to ‘LiveScript’, and then ‘JavaScript’.

Between 1996 and 1997, the European Computer Manufacturers Association (ECMA) standardized JavaScript. After that, 3 revisions of the JavaScript have been done.

In ES5 (2009), Node.js was introduced to use JavaScript as a server-side language. The ES6 (2015) was a significant revision of JavaScript, introducing advanced features into JavaScript.

Currently, JavaScript has reached the version ES14. ES14 (ECMAScript 2023) the 14th version, was released in June 2023.

Client-Side JavaScript

Client-side JavaScript is the most common form of the language. The script should be included in or referenced by an HTML document for the code to be interpreted by the browser.

It means that a web page need not be a static HTML but can include programs that interact with the user, control the browser, and dynamically create HTML content.

The JavaScript client-side mechanism provides many advantages over traditional CGI server-side scripts. For example, you might use JavaScript to check if the user has entered a valid e-mail address in a form field.

The JavaScript code is executed when the user submits the form, and only if all the entries are valid they would be submitted to the Web Server.

JavaScript can be used to trap user-initiated events such as button clicks, link navigation, and other actions that the user initiates explicitly or implicitly.

The Popular client-side libraries for JavaScript development are ReactJS, NextJS, Vue JS, Angular JS, etc.

Server-Side JavaScript

In the early days, JavaScript was used for front-end development to add behaviors to HTML pages. Since 2009, JavaScript is also used as a server-side programming language to build scalable and dynamic web applications.

Node.js is one of the best and most popular JavaScript runtime environments for building the server of applications using JavaScript. Using Node.js, we can execute the JavaScript code outside the browser and manage the server task. The server tasks can be an interaction with the database, APIS, file handling, or maybe network communication. Due to the event-driven architecture of Node.js, it is faster than other server-side programming languages.

Advantages of JavaScript

The merits of using JavaScript are −

Less server interaction − You can validate user input before sending the page off to the server. This saves server traffic, which means less load on your server.
Immediate feedback to the visitors − They don’t have to wait for a page reload to see if they have forgotten to enter something.
Increased interactivity − You can create interfaces that react when the user hovers over them with a mouse or activates them via the keyboard.
Richer interfaces − You can use JavaScript to include such items as drag-and-drop components and sliders to give a Rich Interface to your site visitors.

Limitations of JavaScript

We cannot treat JavaScript as a full-fledged programming language. It lacks the following important features −

Client-side JavaScript does not allow the reading or writing of files. This has been kept for security reasons.
JavaScript cannot be used for networking applications because no such support is available.
JavaScript doesn’t have any multi-threading capabilities.

Imperative vs. Declarative JavaScript

The imperative and declarative is a programming paradigm, and JavaScript follows both.

Imperative JavaScript − In imperative JavaScript, we write code in the manner that the code describes the steps to get the output. So, we are concerned about the code execution flow and output both. For example, to sum all array elements, if we write code for loop, it explains each step to get the sum.
Declarative JavaScript − In declarative JavaScript, we don’t need to worry about execution flow, but we should get the correct output at the end. For example, we use a built-in array.reduce() method to get a sum of array elements. Here, we don’t concern about how reduce() method is implemented in the library.

JavaScript Development Tools

One of the major strengths of JavaScript is that it does not require expensive development tools. You can start with a simple text editor such as Notepad. Since it is an interpreted language inside the context of a web browser, you don’t even need to buy a compiler.

Here are various free tools which can be helpful while developing applications with JavaScript.

Visual Studio Code (VS Code) − The VS Code is a code editor used by most developers to write JavaScript code. It is feature rich and contains various extensions that can increase the productivity of any developer.
Chrome dev tools − Programmers may use the Chrome dev tools to debug the JavaScript code. However, they can use the debugging tool of any browser as most browser comes with it.

The above 2 tools increase the productivity of the developer for writing the code. Furthermore, you may use other tools like Git for version controlling, Webpack to build your application, etc.

Where is JavaScript Today?

In 2015, the ES6 version of JavaScript was launched with significant enhancements, including object-oriented concepts, anonymous functions, template literals, etc. In June 2023, the ES14 (ECMAScript 2023), the 14th version of JavaScript was launched.