The prototype library encapsulates AJAX in a cross-browser manner and adds new functionality with a custom Ajax object.
The second parameter is a simple javascript object created on the fly. It has a property named "method" with the value "get" and another property named "onComplete" with the value "showResponse". When the function is called, it creates a new platform-independent Ajax request which talks to the server using the get method. When the request is complete, it calls the showResponse() method, which manipulates and outputs the data.
function getAjax(){
var myAjax = new Ajax.Request(
"test.html",
{
method: 'get',
onComplete: showResponse
}
);
} // end function
function showResponse(originalRequest){
alert (originalRequest.responseText);
} // end function