Simple AJAX optimization

When ever we write an ajax code to create the AJAX objectwe tend to do it like:

function createAjaxObject()
{
if(window.XMLHttpRequest)
{
ajaxObject =  new XMLHttpRequest();
return ajaxObject;
}
else if(window.ActiveXObject)
{
ajaxObject = new ActiveXObject(”Microsoft.XMLHTTP”);
return ajaxObject;
}
else if(document.ActiveXObject)
{
ajaxObject = new ActiveXObject(”Msxml2.XMLHTTP”);
reutrn ajaxObject;
}
else
{
return null ;
}

}

Now consider a situation when we need to make large no of AJAX calls, the whole loop is called multiple times, which is not required.

So what we can write is:

function createAjaxObject()
{
if(window.XMLHttpRequest)
{
createAjaxObject = function(){ return new XMLHttpRequest(); };
}
else if(window.ActiveXObject)
{
createAjaxObject = function(){ return new ActiveXObject(”Microsoft.XMLHTTP”); };
}
else if(document.ActiveXObject)
{
createAjaxObject = function(){ return new ActiveXObject(”Msxml2.XMLHTTP”); };
}
else
{
createAjaxObject = function(){ return null ;};
}
return createAjaxObject();
}

If we do this it will rewrite the function after it is first called with the most suitable object it can handel.