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JavaScript Variables:

gopim — Mon, 06 Jul 2009 09:29:35 +0000

As with algebra, JavaScript variables are used to hold values or expressions.

A variable can have a short name, like x, or a more descriptive name, like car name.

Rules for JavaScript variable names:

Variable names are case sensitive (y and Y are two different variables)
Variable names must begin with a letter or the underscore character

Note: Because JavaScript is case-sensitive, variable names are case-sensitive.

JavaScript Comments:

gopim — Mon, 06 Jul 2009 09:20:03 +0000

Comments can be added to explain the JavaScript, or to make the code more readable.

Single line comments start with //:

The following example uses single line comments to explain the code:

Example

JavaScript Multi-Line Comments

Multi line comments start with /* and end with */.

Example

What is JavaScript Blocks?

gopim — Mon, 06 Jul 2009 09:14:53 +0000

JavaScript statements can be grouped together in blocks.
Blocks start with a left curly bracket {, and ends with a right curly bracket }.
The purpose of a block is to make the sequence of statements execute together.

Example

What is JavaScript Statements?

gopim — Mon, 06 Jul 2009 09:13:01 +0000

A JavaScript statement is a command to a browser. The purpose of the command is to tell the browser what to do.

This JavaScript statement tells the browser to write “Hello World” to the web page:

document.write(“Hello World”);

How to use an external Javascript?

gopim — Mon, 06 Jul 2009 09:08:09 +0000

If you want to run the same JavaScript on several pages, without having to write the same script on every page, you can write a JavaScript in an external file.

Save the external JavaScript file with a .js file extension.

Note: The external script cannot contain the

Where to put JavaScript?

gopim — Mon, 06 Jul 2009 09:02:50 +0000

JavaScript in a page will be executed immediately while the page loads into the browser. This is not always what we want. Sometimes we want to execute a script when a page loads, other times when a user triggers an event.

Scripts in

Scripts to be executed when they are called, or when an event is triggered, go in the head section.

If you place a script in the head section, you will ensure that the script is loaded before anyone uses it.

Example:

Scripts in

Scripts to be executed when the page loads go in the body section.

If you place a script in the body section, it generates the content of a page.

Example

Scripts in and

We can place an unlimited number of scripts in your document, so we can have scripts in both the body and the head section.

Basic structure of Java script:

gopim — Mon, 06 Jul 2009 08:54:47 +0000

What is Java script?

gopim — Mon, 06 Jul 2009 08:51:34 +0000

Its real name is ECMA script invented byBrendan Eich.

JavaScript was designed to add interactivity to HTML pages
JavaScript is a scripting language
A scripting language is a lightweight programming language
JavaScript is usually embedded directly into HTML pages
JavaScript is an interpreted language (means that scripts execute without preliminary compilation)

Note: Java and JavaScript are two completely different languages in both concept and design.

What is Common Language Specification (CLS)?

gopim — Fri, 03 Jul 2009 12:06:26 +0000

A set of base rules to which any language targetting the CLI should conform in order to interoperate with other CLS-compliant languages. The CLS rules define a subset of the Common Type System.

What is Common Language Runtime (CLR)?

gopim — Fri, 03 Jul 2009 11:49:04 +0000

The Common Language Runtime (CLR)

is the virtual machine component of Microsoft’s .NET initiative. It is Microsoft’s implementation of the Common Language Infrastructure (CLI) standard, which defines an execution environment for program code

The Common Language Runtime (CLR) is the virtual machine component of Microsoft’s .NET initiative. It is Microsoft’s implementation of the Common Language Infrastructure (CLI) standard, which defines an execution environment for program code.