Ajax request data and status codes in native and jquery packages

Native AJAX Request data

Btn.addeventlistener (' click ',function(){        if(window. XMLHttpRequest) {varXHR =Newwindow.        XMLHttpRequest (); }Else{            //compatible with IE browser            varXHR =NewActiveXObject (' Microsoft.XMLHTTP '); }        //Request Method Get/post        //Request URL        //ture asynchronous request; false synchronous requestXhr.open (' Get ', '/ajax/getdata ',true); //changes to XHR binding event listening state (status code see below)Xhr.onreadystatechange =function(){            if(Xhr.readystate = = 4 && xhr.status = 200) {console.log (xhr.responsetext); }        }        //Send Request Data//get method The send parameter is empty or nullXhr.send (); });

Ajax encapsulation implemented by JQuery

// jQuery    $ ('. Btn '). On (' click ',function() {            $.ajax ({                URL:'/ajax/getdata ',                type:') Get ',                dataType:' json ',                // successfully execute function                success:functions  (response,status) {                   console.log (responsetext);                }            );        });

Xhr.readystate Status Code

0:unsend//Current request not yet sent

1:opened//url Address is open

2:headers_received//Response header information has been received

3:loading//Primary return data is being prepared for processing on the server

The contents of the 4:done//response body have been successfully returned to the client

Xhr.status Server Status Code

200 and starting with 2: success (the body of the response has successfully returned to the client)

301: Permanent Redirect/Transfer

302: Temporary REDIRECT/transfer

304: This time gets the content is read the cache

400: Incorrect parameter for server with client

401: No Access

404: Access address does not exist

500: Unknown server error

501: Server overload

The data is not complete for reference only----------

Ajax request data and status codes in native and jquery packages