JavaScript HTML DOM Objects

Screen:

Screen object object contains information about the display screen of the client. The object provides information about the user's video display and color settings. JavaScript runtime engine automatically creates these settings.

There are various properties associated with the Screen object.

Properties of Screen Object:

• availHeight
• availWidth
• bufferDepth
• colorDepth
• deviceXDPI
• deviceYDPI
• fontSmoothingEnabled
• height
• logicalXDPI
• logicalYDPI
• pixelDepth
• updateInterval
• width

In the next sections, the usage, syntax and explanation with examples of each of the properties of the Screen object will be discussed.

Navigator:

Navigator object is an object that is automatically created JavaScript runtime engine. Navigator contains information about the client browser.

This object is used to obtain information about the type of browser being used to access the page. Using this information, the user can be directed to a different page or carry out tasks or functions depending upon the user’s browser.

The following list gives some of the properties and methods of the Navigator object.

Properties of Navigator Object:

• appCodeName

• appMinorVersion

• appName

• appVersion

• browserLanguage

• cookieEnabled

• cpuClass

• onLine

• platform

• systemLanguage

• userAgent

• userLanguage

Methods of Navigator Object:

• javaEnabled()
• taintEnabled()

History:

Like the Screen Object, the History object is also automatically created object by the JavaScript runtime engine. Browsers store the list of the user’s previously visited URLs. Using this list, the user navigates to previously visited web pages using the back and forward buttons in the browser. This list of URLs is called the browser's history. It's stored in the form of a list that can be accessed by JavaScript. History object can be assessed by using the window.history property. The History object is a part of a Window object.

The following list gives some of the properties and methods of the History object.

Property of History Object:

• length

Methods of History Object:

• back()
• forward()
• go()

Syntax and explanation with examples of History object properties and methods are discussed in coming sections.

Location:

Location object contains information about the current URL and thus this object provides access and control over the URL of the current window. But one important point to note in this context is that it cannot modify the URL displayed in the browser's address box and thus adds security in its usage. Since it is part of the Window object it is accessed using the window.location property.

Location Object is automatically created by the JavaScript runtime engine. The following list gives some of the properties and methods of the Location object.

Properties of Location Object:

• hash
• host
• hostname
• href
• pathname
• port
• protocol
• search

Methods of Location Object:

• assign()
• reload()
• replace()