Class 9 Computer Science Web Scripting Java Script Notes

Download Class 9 Computer Science Web Scripting Java Script Notes in PDF format. All Revision notes for Class 9 Computer Science have been designed as per the latest syllabus and updated chapters given in your textbook for Computer Science in Standard 9. Our teachers have designed these concept notes for the benefit of Grade 9 students. You should use these chapter wise notes for revision on daily basis. These study notes can also be used for learning each chapter and its important and difficult topics or revision just before your exams to help you get better scores in upcoming examinations, You can also use Printable notes for Class 9 Computer Science for faster revision of difficult topics and get higher rank. After reading these notes also refer to MCQ questions for Class 9 Computer Science given our website

Web Scripting Java Script Class 9 Computer Science Revision Notes

Class 9 Computer Science students should refer to the following concepts and notes for Web Scripting Java Script in standard 9. These exam notes for Grade 9 Computer Science will be very useful for upcoming class tests and examinations and help you to score good marks

Web Scripting Java Script Notes Class 9 Computer Science

Introduction and History of Java Script
 
JavaScript started life as Live Script, but Netscape changed the name, possibly because of the excitement being generated by Java.to JavaScript. JavaScript is a lightweight, interpreted programming language with object-oriented capabilities that allows you to build interactivity into otherwise static HTML pages. The general-purpose core of the language has been embedded in Netscape, Internet Explorer, and other web browsers. 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 no longer be static HTML, but can include programs that interact with the user, control the browser, and dynamically create HTML content.
 
Objectives and Properties
 
JavaScript is:
• 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
 
The general-purpose core of the language has been embedded in Netscape, Internet Explorer, and other web browsers
 
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 do not 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 with JavaScript:

• We cannot treat JavaScript as a full-fledged programming language.
• 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 does not have any multithreading or multiprocess capabilities.
 
JavaScript Syntax:
A JavaScript consists of JavaScript statements that are placed within the <script>... </script> HTML tags in a web page.
 
Class 9 Computer Science Web Scripting Java Script Notes
 
The script tag takes two important attributes:
• Language: This attribute specifies what scripting language you are using. Typically, its value will be JavaScript.
• Type: This attribute is what is now recommended to indicate the scripting language in use and its value should be set to "text/javascript".
 
 
Your First JavaScript Script:
Let us write an example to print out "Hello World".
Class-9-Computer-Science-Web-Scripting-Java-Script-Notes-unlocked 1
So above code will display following result:
Class-9-Computer-Science-Web-Scripting-Java-Script-Notes-unlocked 2
Variables & Operators
 
Variable constraints,
 
JavaScript Data Types: One of the most fundamental characteristics of a programming language is the set of data types it supports. These are the type of values that can be represented and manipulated in a programming language.
 
JavaScript allows you to work with three primitive data types:
 
• Numbers eg. 123, 120.50 etc.
• Strings of text e.g. "This text string" etc.
• Boolean e.g. true or false.
Java does not make a distinction between integer values and floating-point values.
 
JavaScript Variables
 
Variable is the stored memory location that can hold a value in it. Variables are declared with the var keyword. Storing a value in a variable is called variable initialization.
Example:
Class-9-Computer-Science-Web-Scripting-Java-Script-Notes-unlocked 3
 
JavaScript Variable Scope:
 
The scope of a variable is the region of your program in which it is defined. JavaScript variable will have only two scopes.
 
• Global Variables: A global variable has global scope which means it is defined everywhere in your JavaScript code.
• Local Variables: A local variable will be visible only within a function where it is defined. Function parameters are always local to that function.
Class-9-Computer-Science-Web-Scripting-Java-Script-Notes-unlocked 4
This produces the following result:
Class-9-Computer-Science-Web-Scripting-Java-Script-Notes-unlocked 5

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