In this lesson are presented the JavaScript level one browser objects: navigator and history.

1. navigator object

The navigator object gives some informations about what browser is running your code.
You can use it to collect data about what browsers visit your sites. For example, if you know that Internet Explorer doesn’t support some code, you can test:
      if ( window.navigator.appName == "Microsoft Internet Explorer" ).

navigator object properties


- The following example writes in the page the return values of these properties (used on Firefox).
<script type="text/javascript"><!--
document.write('appCodeName - '+ navigator.appCodeName+ '<br />');
document.write('appName - '+ navigator.appName+ '<br />');
document.write('appVersion - '+ navigator.appVersion+ '<br />');
document.write('cookieEnabled - '+ navigator.cookieEnabled+ '<br />');
document.write('platform - '+ navigator.platform+ '<br />');
document.write('userAgent - '+ navigator.userAgent+ '<br />');
--></script>
- The result is:
appCodeName - Mozilla
appName - Netscape
appVersion - 5.0 (Windows; en-US)
cookieEnabled - true
platform - Win32
userAgent - Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.2.13) Gecko/20101203 Firefox/3.6.13

navigator object methods


- The following example writes a message about if Java is enabled or not.
<script type="text/javascript"><!--
if (navigator.javaEnabled) document.write('Java enabled');
else document.write('Java is not enabled');
--></script>

2. history object

The history object contains a list of URLs that the user visited within the current browser window and some features to navigate that list. It is part of the window object and is accessed through the window.history

history object properties

- Example:
<script type="text/javascript"><!--
document.write(window.history.length);      // 3
--></script>

history object methods


- The fallowing example creates a button to go back two pages:
<script type="text/javascript"><!--
function goBack() {
  window.history.go(-2);
}
--></script>
<button onclick="goBack()">Go Back 2</button>

Daily Test with Code Example

HTML
CSS
JavaScript
PHP-MySQL
Which meta tag provides a short description of the page?
<meta content="..."> <meta description="..."> <meta http-equiv="...">
<meta name="description" content="70-160 characters that describes the content of the page" />
Which CSS property is used to stop the wrapping effect of the "float"?
clear text-align position
#some_id {
  clear: both;
}
Click on the method which gets an array with all the elements in the document that have a specified tag name.
getElementsByName() getElementById() getElementsByTagName()
var divs = document.getElementsByTagName("div");
var nr_divs = divs.length;
alert(nr_divs);
Indicate the PHP function which returns the number of elements in array.
is_[) count() strlen()
$arr =[7, 8, "abc", 10);
$nri = count($arr);
echo $nri;        // 4
navigator and history objects

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