XMLHttpRequest (XHR): It is used for asynchronous communication between client and server and send HTTP or HTTPS requests to a web server and load the server response data back into the script.
It performs following operations:
- Updates the webpage without reloading it.
- Receive data from a server - after the page has loaded.
- Send data to a server - in the background.
Create an XMLHttpRequest Object
var xmlHttpRqst = new XMLHttpRequest(); For All modern browsers (Chrome, Firefox, IE7+, Edge, Safari, Opera)
var xmlHttpRqst = new ActiveXObject("Microsoft.XMLHTTP"); For IE5 and IE6
Properties of XMLHttpRequest object are as follows:
||It is called whenever readystate attribute changes. It must not be used with synchronous requests.
represents the state of the request. It ranges from 0 to 4.
0 : request not initialized
1 : server connection established
2 : request received
3 : processing request
4 : request finished and response is ready
||returns response as text.
||returns response as XML.
Returns the status-number of a request.
200 : "OK"
403 : "Forbidden"
404 : "Not Found"
||Returns the status-text (e.g. "OK" or "Not Found")