AJAX XML

AJAX can be used for interactive communication with an XML file. The example below shows how a web page can fetch information from an XML file using AJAX technology.
Course information will be listed here.
This example consists of four files:
  1. a client-side simple HTML form,
  2. a client-side JavaScript file ShowCourse.js,
  3. a server-side XML file CourseList.xml, and
  4. a server-side PHP file GetCourse.php.
The HTML Form
It contains a simple HTML form and a link to a JavaScript file: 

<html>
  <head><script src="ShowCourse.js"></script></head>
  <body>
    <form>
      <select name="courses" onChange="showCourse( this.value )">
        <option value="">Select a course:</option>
        <option value="260">CSCI260</option>
        <option value="370">CSCI370</option>
        ...
      </select>
    </form>
    <span id="txtHint">Course information will be listed here.</span>
  </body>
</html>

It is just a simple HTML form with a simple drop down box called courses. A span called txtHint is used as a placeholder for information retrieved from the web server. When the user selects data, a function called showCourse is executed. The execution of the function is triggered by the onChange event. In other words: Each time the user changes the value in the drop down box, the function showCourse is called.