JAVASCRIPT

By- SANDEEP KUMAR PATEL

JavaScript

JavaScript is a lightweight, interpreted programming language. It is designed for creating network-centric applications. It is complimentary to and integrated with Java. JavaScript is very easy to implement because it is integrated with HTML. It is open and cross-platform.

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 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, Internet Explorer, 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

version of JavaScript:

• The Original JavaScript ES1 ES2 ES3 (1997–1999)
• The First Main Revision ES5 (2009)
• The Second Revision ES6 (2015)
• The Yearly Additions (2016, 2017, 2018)

Did You Know?

JavaScript and Java are completely different languages, both in concept and design.

JavaScript was invented by Brendan Eich in 1995, and became an ECMA standard in 1997.

ECMA-262 is the official name of the standard. ECMAScript is the official name of the language.

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.

Why to Learn Javascript

Javascript is a MUST for students and working professionals to become a great Software Engineer specially when they are working in Web Development Domain. I will list down some of the key advantages of learning Javascript:

• Javascript is the most popular programming language in the world and that makes it a programmer’s great choice. Once you learnt Javascript, it helps you developing great front-end as well as back-end softwares using different Javascript based frameworks like jQuery, Node.JS etc.
• Javascript is everywhere, it comes installed on every modern web browser and so to learn Javascript you really do not need any special environment setup. For example Chrome, Mozilla Firefox , Safari and every browser you know as of today, supports Javascript.
• Javascript helps you create really beautiful and crazy fast websites. You can develop your website with a console like look and feel and give your users the best Graphical User Experience.
• JavaScript usage has now extended to mobile app development, desktop app development, and game development. This opens many opportunities for you as Javascript Programmer.
• Due to high demand, there is tons of job growth and high pay for those who know JavaScript. You can navigate over to different job sites to see what having JavaScript skills looks like in the job market.

Great thing about Javascript is that you will find tons of frameworks and Libraries already developed which can be used directly in your software development to reduce your time to market.

There could be 1000s of good reasons to learn Javascript Programming. But one thing for sure, to learn any programming language, not only Javascript, you just need to code, and code and finally code until you become expert.

There are many useful Javascript frameworks and libraries available

• Angular
• React
• jQuery
• Vue.js
• Ext.js
• Ember.js
• Meteor
• Mithril
• Node.js
• Polymer
• Aurelia
• Backbone.js

Applications of Javascript Programming

As mentioned before, Javascript is one of the most widely used programming languages (Front-end as well as Back-end). It has it’s presence in almost every area of software development. I’m going to list few of them here:

• Client side validation — This is really important to verify any user input before submitting it to the server and Javascript plays an important role in validting those inputs at front-end itself.
• Manipulating HTML Pages — Javascript helps in manipulating HTML page on the fly. This helps in adding and deleting any HTML tag very easily using javascript and modify your HTML to change its look and feel based on different devices and requirements.
• User Notifications — You can use Javascript to raise dynamic pop-ups on the webpages to give different types of notifications to your website visitors.
• Back-end Data Loading — Javascript provides Ajax library which helps in loading back-end data while you are doing some other processing. This really gives an amazing experience to your website visitors.
• Presentations — JavaScript also provides the facility of creating presentations which gives website look and feel. JavaScript provides RevealJS and BespokeJS libraries to build a web-based slide presentations.
• Server Applications — Node JS is built on Chrome’s Javascript runtime for building fast and scalable network applications. This is an event based library which helps in developing very sophisticated server applications including Web Servers.

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 reason.
• JavaScript cannot be used for networking applications because there is no such support available.
• JavaScript doesn’t have any multi-threading or multiprocessor capabilities.

Once again, JavaScript is a lightweight, interpreted programming language that allows you to build interactivity into otherwise static HTML pages.

JavaScript Can Change HTML Content

One of many JavaScript HTML methods is getElementById().

The example below “finds” an HTML element (with id=”demo”), and changes the element content (innerHTML) to “Hello JavaScript”:

document.getElementById(“demo”).innerHTML = “Hello JavaScript”;

JavaScript in <head> or <body>

You can place any number of scripts in an HTML document.

Scripts can be placed in the <body>, or in the <head> section of an HTML page, or in both.

JavaScript in <head>

In this example, a JavaScript function is placed in the <head> section of an HTML page. The function is invoked (called) when a button is clicked:

Example

<!DOCTYPE html>
<html>

<head>
<script>
function myFunction() {
document.getElementById(“demo”).innerHTML = “Paragraph changed.”;
}
</script>
</head>
<body>

<h1>A Web Page</h1>
<p id=”demo”>A Paragraph</p>
<button type=”button” onclick=”myFunction()”>Try it</button>

</body>
</html>

Thank YOU….!!!