XML and JavaScript in Mozilla

Access Tag Attributes

Storing information in XML files in the form of attributes is very common. Consequently, it is important that we are able to access attributes in XML files. In our example XML file, we have stored various employee details, including id, sex, and age, in the <employee> tag. To extract the age of the first employee, we could use the following code:

document.write(employees[0].getAttribute("age"));

The above code will output 20. The code used the getAttribute() method on the employees[0] object. Alternatively, we could use the following code to obtain the same result:

document.write(xmlDoc.getElementsByTagName("company")[0].getElementsByTagName("employee")[0]  
.getAttribute("age"));

Now, suppose you want to display the details of all employees (id, sex, age) in a tabular form. To do this, we must loop through all the <employee> tags. Following is the entire code to do this (excluding the code that loads the file):

var companies=xmlDoc.getElementsByTagName("company");  
var employees=companies[0].getElementsByTagName("employee");  
document.write('<table border="1">');  
document.write('<tr><th>id</th><th>Sex</th><th>Age</th></tr>');  
for(var i=0; i<employees.length; i++) {  
 document.write('<tr>');  
 document.write('<td>' + employees[i].getAttribute("id") + '</td>');  
 document.write('<td>' + employees[i].getAttribute("sex") + '</td>');  
 document.write('<td>' + employees[i].getAttribute("age") + '</td>');  
 document.write('</tr>');  
}  
document.write('<table>');

The output of the above code in Mozilla looks like this:

Is it Possible to Write to an XML File?

No, it’s not possible to write to an XML file using client-side JavaScript. You can manipulate all the contents of an external XML file and use it for display purposes in your client-side JavaScript application, but it is not possible, for instance, to take input from the user, and make changes to the XML file using JavaScript.

Conclusion

We now know how to test for Mozilla, load an XML document using JavaScript, and manipulate the contents of an XML file using JavaScript in Mozilla. Using XML and client-side JavaScript, several simple applications can be created:

• you could use XML files to store small databases, then use JavaScript to display the data according to your needs
• you could create something like a news “ticker”, where you store the news items in a XML file and your JavaScript reads the contents of the file and ticks the news items on the screen

These are just a few examples where XML and client-side JavaScript could be used. I hope this article has given you an introductory idea of using XML and client-side JavaScript in Mozilla.