In JavaScript, to call a URL for usage in an Ajax application, an XMLHttpRequest object must be created. This was described in a previous post:
JavaScript: Creating XMLHttpRequest object for Ajax
Once the XMLHttpRequest (XHR) object is created, a URL can be called by using the XHR’s open method, as follows:
objXHR.open('GET','http://myURL.com',true);
The three parameters passed to the open method are as follows:
1: The method by which the HTTP should be retrieved: GET or POST
2: The requested URL. A relative or absolute URL may be used here. If an absolute URL is being used, most browsers implement a same-origin policy, meaning the URL being requested must be on the same domain as the domain from which the URL is being requested.
3: How the request should be issued: True for asynchronous; False for synchronous.
After the XHR object has opened a request, send the request.
