Joey Javas

The XMLHttpRequest object is initialized differently in earlier versions of Internet Explorer as compared to Firefox.

As of Internet Explorer 7, an XMLHttpRequest be can be initialized simply with:

new XMLHttpRequest();

The preceding always worked with Firefox. In earlier versions of Internet Explorer, however, the libraries differed on how to initialize XMLHttpRequest. For this reason, both of the following calls have to be attempted as well:

new ActiveXObject('Msxml2.XMLHTTP');
new ActiveXObject('Microsoft.XMLHTTP');

This should be done as a try/catch block, with the call that will work in Firefox and Internet Explorer 7 coming first as it is the most likely to succeed.

try {
  var objXHR = new XMLHttpRequest();
} catch (e) {
try {
  var objXHR = new ActiveXObject('Msxml2.XMLHTTP');
} catch (e) {
try {
  var objXHR = new ActiveXObject('Microsoft.XMLHTTP');
} catch (e) {
  document.write('XMLHttpRequest not supported'); }
}
}

Related Articles:
Creating an XMLHttpRequest Object for Ajax
JavaScript Try Catch Finally

This entry was posted on Monday, September 10th, 2007 at 10:26 pm and is filed under JavaScript, Software, Technology, Web, Web 2.0, programming. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.