AJAX - Browser Support-alljchome-开发者的教程家园

AJAX Tutorial

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AJAX - Browser Support

All the available browsers cannot support AJAX. Here is a pst of major browsers that support AJAX.

Mozilla Firefox 1.0 and above.

Netscape version 7.1 and above.

Apple Safari 1.2 and above.

Microsoft Internet Explorer 5 and above.

Konqueror.

Opera 7.6 and above.

When you write your next apppcation, do consider the browsers that do not support AJAX.

NOTE − When we say that a browser does not support AJAX, it simply means that the browser does not support the creation of Javascript object – XMLHttpRequest object.

Writing Browser Specific Code

The simplest way to make your source code compatible with a browser is to use try...catch blocks in your JavaScript.

<html>
   <body>
      <script language = "javascript" type = "text/javascript">
         <!-- 
         //Browser Support Code
         function ajaxFunction() {
            var ajaxRequest;  // The variable that makes Ajax possible!

            try {
               // Opera 8.0+, Firefox, Safari 
               ajaxRequest = new XMLHttpRequest();
            } catch (e) {

               // Internet Explorer Browsers
               try {
                  ajaxRequest = new ActiveXObject("Msxml2.XMLHTTP");
               } catch (e) {
                  
                  try {
                     ajaxRequest = new ActiveXObject("Microsoft.XMLHTTP");
                  } catch (e) {

                     // Something went wrong
                     alert("Your browser broke!");
                     return false;
                  }
               }
            }
         }
         //-->
      </script>
      
      <form name =  myForm >
         Name: <input type =  text  name =  username  /> <br />
         Time: <input type =  text  name =  time  />
      </form>
      
   </body>
</html>

In the above JavaScript code, we try three times to make our XMLHttpRequest object. Our first attempt −

ajaxRequest = new XMLHttpRequest();

It is for Opera 8.0+, Firefox, and Safari browsers. If it fails, we try two more times to make the correct object for an Internet Explorer browser with −

ajaxRequest = new ActiveXObject("Msxml2.XMLHTTP");

ajaxRequest = new ActiveXObject("Microsoft.XMLHTTP");

If it doesn t work, then we can use a very outdated browser that doesn t support XMLHttpRequest, which also means it doesn t support AJAX.

Most pkely though, our variable ajaxRequest will now be set to whatever XMLHttpRequest standard the browser uses and we can start sending data to the server. The step-wise AJAX workflow is explained in the next chapter.

AJAX - Browser Support

Writing Browser Specific Code

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