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.JavaScript&more Tutorial
 
I have visited many  publications on the Internet and have used some of them to choose and prepare the lessons for my students. Thank you to all authors, who has published free their work. My work is FREE for all on the net, too. I hope this Tutorial will help to everyone who wants to make attractive web pages! Enjoy!  The main lessons are: Go to  the Index File



 
What is Java Script?

It is a scripting language developed by Netscape to add interactivity and power to web documents.    Examples  of  Java Script include live clocks, rollover effects, scrollers, and so on. JavaScript differs from most other programmning languages
in that it is relatively easy  to  master, even  for  people  who  have absolutely no programming experiences whatsoever.

Why learn JavaScript?
With html, you are restricted to creatingstatic, non interactive webpages. This, in today's internet standards, is unacceptable. With JavaScript, you can change that. 

Getting Started: Setting Up your code.
Where do your JavaScript codes go? ..anywhere inside the <html> tags of your page. The beginning of your code begins with <script> and ends with </script>

<html>
   <head>
       <title>example</title>
   </head>
 <body>
   <script language="JavaScript">
   <!--
                 document.write("This text is written using JavaScript.")
   //-->
   </script>
 </body>
</html>

The tags <!-- and //--> are comment tags and should always be included to help hide your code against older browsers. The only "functional part" of this script is the document.write("....")part. 


OBJECTS
The script document.write("I am learning JavaScript") write a line of text.

"document" is the object in the above example.
"write" is the method of this object.

JavaScript is a language of objects and almost all of them have both methods and properties. 
 

Document Object:
Properties

bgColor (changes background color) 
lastModified (gives date of document's last change) 
document.write (gives date of document's last change) 
referrer (gives URL of the page that linked here) 
fgColor (changes foreground color) 

Methods

write (writes something) 
writeln (writes in new line)


FUNCTIONS


They achieve more complex task and are not executed until you call upon them. 
The basic syntax of a function is:

    function name
    {
    function's code
    }

Example:

    function test()
    {
    document.write("Hello, World!")
    }

It will be not enough to put this in the <script></<script> tags so to see the text on the screen. The function must be implement by 

    test()

This function doesn't use parameters. 

In the next example they are used:

<html>
<head>
  <title>Example</title>
</head>
<body>
  <script>
   var x=prompt("Please enter your age")
   function days(age)
       {
        var time=age*365
        alert("You have lived"+time+"days")
        }
    days(x)
  </script>
</body>
</html>

The above function doesn't return a value.  It only take a value and use it to
show the result on the screen. 

There are many functions which can return a value for future using.

Lets see the example:

<html>
<head>
<title>function</title>
</head>
<body>
 <script>
var a=prompt("Please enter the length of the rectangle: ")
var b=prompt("Please enter the width of the rectangle: ")
   function area(a,b)
       {
       var S=a*b
       return S
       }
    document.write("The area is "+area(a,b))
 </script>
</body>
<html>

Now we would like to implement for you an example, which only will teach and show you the possibilities of some functions:

The code is written here:

<html>
 <head>
   <title>FUNCTIONS</title>
 </head>
<body>
 <script>
   function MAIN_EXAMPLE()
  {
  var x=window.confirm("This is a question and the continuation is depended of your
                                                  answer! So, are you sure you are OK?")
  if (x)
      window.alert("Good! This answer is shown because you have clicked the button OK!")
  else
      window.alert("Too bad! This answer is shown because  you haven't clicked 
                                  the button OK!")
      alert("This message is shown with a method ALERT of the object WINDOW! 
                  You can use it many times in your script!")
      var y=window.prompt("Now we are using a method PROMPT of the object 
                                                     WINDOW! Your answer will be taken as a value of 
                                                     the parameter Y! So, please, enter your name instead 
                                                    of the text undefined!") 
      window.alert("The result of PROMPT is: "+y)
      document.write("This is shown with a method WRITE of the object DOCUMENT! 
                                         It is included in the body of the function!")
   }
   window.alert("We are using a method ALERT of the object WINDOW! 
                              This part is not included in a function! Let us start the 
                              execution of the function   MAIN_EXAMPLE!") 
  MAIN_EXAMPLE()
  document.writeln("Be patient! Just now started the text, which isn't included in 
                                       the function! We are using again the method WRITE of the 
                                       object DOCUMENT!")
  </script>
 </body>
</html>


 

To continue with Event handlers continue