Math object has two constant : Math.PI and Math.E

Math object has following functions:

- Math.abs(val1);

It will give absolute value of val1.

- Math.max(val1,val2);

This fuction will return maximum value from val1 and val2.

- Math.random();

This function will return a random number between 0 and 1.

- Math.floor(val1)

This function will returns decimal value of val1

Arrays are created by using new Array() in Java Script.

For example : var employees = new Array();

The elements to this array is assigned as follows :

employees[0] = "Kumar"

employees[1] = "Fedrick"

Files can be read and written by using java script functions – fopen(),fread() and fwrite().

The function fopen() takes two parameters – 1. Path and 2. Mode (0 for reading and 3 for writing). The fopen() function returns -1, if the file is successfully opened.

Ex: file=fopen(getScriptPath(),0);

The function fread() is used for reading the file content.

Ex: str = fread(file,flength(file));

The function fwrite() is used to write the contents to the file.

Ex(): file = fopen("c:\MyFile.txt", 3);// opens the file for writing

fwrite(file, str);// str is the content that is to be written into the file.

NaN stands for ‘not-a-number’. The function isNaN determines the argument or the value is a NaN. The function returns true if the argument is not a number, otherwise returns false.

Windows object is top level object in Java script. It contains several other objects such as, document, history, location, name, menu bar etc., in itself. Window object is the global object for Java script that is written at client-side.

Information pertaining to the client browser and system is returned by the navigator object of JavaScript. Navigator object is the top level object for all users.

To send the characters that can not be specified in a URL should be converted into their equivalent hex encoding. To perform this task the methods encodeURI() and decodeURI() are used.

For example, the following code snippet performs the encoding of URL:

<script type="text/javascript">

          var uri = https://www.mysite.com/city?=Banglore; // original URI

          var ncodeuri=encodeURI(uri);

          document.write("<br />ncodeuri”);

          var dcodeuri = decodeURI(ncodeuri); 

          document.write(“<br>/>dcodeuri”);

</script>

The cursor can set to wait in JavaScript by using the property ‘cursor’ property. The following example illustrates the usage.

window.document.body.style.cursor = "wait"; 

The elements of JavaScript are accessed by their names. By default the browser is accessed by the element ‘windows’ and the page by ‘document’. The corresponding element has user defined names for forms and its elements. For example

var pwd = windows.document.frmLogin.password.value;

assigns the value of the password field of the form fromLogin in the current document, where password is the name of the element and frmLogin is the name of the form. Like wise any form element is accessed.