Archive for the ‘Master CIW Web Site Manager’ category

Every item added in a list has an index. The index of the first item is zero. The index of the last item is one less than the total number of items in the list. The selectedIndex property selects the item according to its index. The syntax of the selectedIndex property is as follows:

The world is full of objects. Each object can be recognized by its unique property. Every object contains methods and events that help the users to use the object. For example, if you are driving a car or pressing the accelerator, it is an event. The increasing of the speed is a method that is invoked when the accelerator is pressed. In a similar way, JavaScript contains many objects. Each object has its own properties, methods, and events. With the help of these properties, methods, and events, the objects can be used to make a Web page or Web site interactive.

A textfield object is a form element that is used to display a single line text. This object is used to display the results of a script calculation, string manipulation, etc. A textfield object can be inserted by using the input tag within the form tag.

For example:

The window object has the unique position of being at the top of the JavaScript object hierarchy. It can be used to access the URL of the window by using its location property, or it can access the content of the window by using its document property. Since all actions are performed in the window, the window object reference is usually omitted.

The document object is related to the content area of a browser window. The document object contains a rich set of properties and methods that help the programmer to insert text and images in an HTML document. The write method is one of the methods of the document object that is used to write contents dynamically on a Web page. The write method can also be used to create a Web page dynamically.

The modulo operator is used to find out the remainder after a division has been completed. Its sign is %. This can be used with integers and floating point numbers.

The following example will demonstrate the use of the modulo operator:

<script language=”javascript”>
var a=10
var b=4
var c=a%b
document.write(c)
</script>

The operator precedence is an arrangement of operators in JavaScript. It decides the priority of the operators in a complex statement. In other words, it decides the order of the execution of operators in a complex statement. If a statement consists of more than one operator, the operators are used according to their priority defined in JavaScript.

JavaScript uses the period (.) to separate components of a hierarchical reference. This convention is adopted from Java. Without the dot notation, referencing the object is not possible. The dot notation is the only way to reference the properties of an object or reference the parent object by the child object.