Javascript: Cross-Browser XMLHttpRequest Implementation

Anatoly Lubarsky — Fri, 08 Feb 2008 23:00:00 GMT

"XMLHttpRequest is an API that can be used by JavaScript, and other web browser scripting languages to transfer XML and other text data between a web page's Client-Side and Server-Side."

Internet Explorer implementation of XMLHttp is ActiveX. However Mozilla based browsers implement XMLHttp, not as an ActiveX control but as a native browser object called XMLHttpRequest.

Therefore it is a common problem when solutions utilizing XMLHttp work fine in one browser but not in the other. The following snippet is a function which creates XMLHttp object in javascript ready for use. Tested in IE and Firefox:

    
    // Create and return XMLHttp object
    function GetXmlHttp()
    {
        var oXmlHttp = null;

        try
        {
            oXmlHttp = new ActiveXObject("Msxml2.XMLHTTP");
        }
        catch(e)
        {
            try
            {
                oXmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
            } 
            catch(oc)
            {
                oXmlHttp = null;
            }
        }

        if ((!oXmlHttp) && (typeof XMLHttpRequest != 'undefined')) 
        {
            oXmlHttp = new XMLHttpRequest();
        }
        
        return oXmlHttp;
    }

Enjoy :)