Create XMLHttpRequest object
XMLHttpRequest is the foundation of AJAX.
All modern browsers (IE7 +, Firefox, Chrome, Safari and Opera) are built-in XMLHttpRequest object.
Note: IE5 / IE6 requires ActiveRequest object.
Send a request to the server
xmlhttp.open("GET","ajax_info.txt",true);
xmlhttp.send();
GET or POST?
Compared with POST, GET easier and faster, and can be used in most cases.
However, in the following cases, please use the POST request:
- Can not use the cache files (files or update the database on the server)
- Sending large amounts of data (POST not limit the amount of data) to the server
- When sending the user input contains unknown character, POST is more stable and more reliable than the GET