Java Script

JavaScript is a programming language that allows you to implement complex things on web pages — every time a web page does more than just sit there and display static information for you to look at — displaying timely content updates, or interactive maps, or animated 2D/3D graphics, or scrolling video jukeboxes, etc. — you can bet that JavaScript is probably involved. It is the third layer of the layer cake of standard web technologies, two of which (HTML and CSS) we have covered in much more detail in other parts of the Learning Area.
  • HTML is the markup language that we use to structure and give meaning to our web content, for example defining paragraphs, headings, and data tables, or embedding images and videos in the page.
  • CSS is a language of style rules that we use to apply styling to our HTML content, for example setting background colors and fonts, and laying out our content in multiple columns.
  • JavaScript is a scripting language that enables you to create dynamically updating content, control multimedia, animate images, and pretty much everything else. (Okay, not everything, but it is amazing what you can achieve with a few lines of JavaScript code.)
The three layers build on top of one another nicely. Let's take a simple text label as an example. We can mark it up using HTML to give it structure and purpose:


                       JavaScript is a very powerful client-side scripting language. JavaScript is used mainly for enhancing the interaction of a user with the webpage. In other words, you can make your webpage more lively and interactive, with the help of JavaScript. JavaScript is also being used widely in game development andMobile application development.
Introduction to JavaScript
History
JavaScript was developed by Brendan Eich in 1995, which appeared in Netscape, a popular browser of that time.
Introduction to JavaScript
The language was initially called LiveScript and was later renamed JavaScript. There are many programmers who think that JavaScript and Java are the same. In fact, JavaScript and Java are very much unrelated. Java is a very complex programming language whereas JavaScript is only a scripting language. The syntax of JavaScript is mostly influenced by the programming language C.
How to Run JavaScript?
Being a scripting language, JavaScript cannot run on its own. In fact, the browser is responsible for running JavaScript code. When a user requests an HTML page with JavaScript in it, the script is sent to the browser and it is up to the browser to execute it. The main advantage of JavaScript is that all modern web browsers support JavaScript. So, you do not have to worry whether your site visitor uses Internet Explorer, Google Chrome, Firefox or any other browser. JavaScript will be supported. Also, JavaScript runs on any operating system including Windows,Linux or Mac. Thus, JavaScript overcomes the main disadvantages of VBScript (Now deprecated) which is limited to just IE and Windows.
Tools You Need
To start with, you need a text editor to write your code and a browser to display the web pages you develop. You can use text editor of your choice including Notepad++, Visual Studio Code, Sublime Text, Atom or any other text editor you are comfortable with. You can use any web browser including Google Chrome, Firefox, Microsoft Edge, Internet Explorer etc.
A Simple JavaScript Code
You should place all your JavaScript code within <script> tags (<script> and </script>) if you are keeping your JavaScript code within the HTML document itself. This helps your browser distinguish your JavaScript code from the rest of the code. As there are other client side scripting languages (Example: VBScript), it is highly recommended that you specify the scripting language you use.  You have to use the type attribute within the <script> tag and set its value to text/javascript like this:
<script type="text/javascript">




































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<html>









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<head>









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    <title>My First JavaScript code!!!</title>









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    <script type="text/javascript">









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        alert("Welcome!!! You are now learning JavaScript.");









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    </script>









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</head>









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<body>









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</body>









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</html>















































Note: type="text/javascript" is not necessary in HTML5. Following code will work.



This code is editable. Click Run to Execute

































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<html>









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<head>









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    <title>My First JavaScript code!!!</title>









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    <script>









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        alert("Welcome!!! You are now learning JavaScript.");









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    </script>









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</head>









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<body>









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</body>









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</html>




































































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