The use of Ajax in jquery

jquery has a lot of encapsulation of Ajax, which makes Ajax very convenient to use and saves a lot of code. 1. Front Code

<%@ page language= "java" contenttype= "text/html; Charset=utf-8 "pageencoding=" UTF-8 "%> <!
DOCTYPE HTML PUBLIC "-//w3c//dtd HTML 4.01 transitional//en" "Http://www.w3.org/TR/html4/loose.dtd" >  
2. Code explanation 
1 The first step in using jquery is to introduce the jquery library, where I put the jquery library under the JS folder under the project root directory.

<!--introduction of jquery Library--
<script type= "Text/javascript" src= "Js/jquery.js" ></script>
 
2 JSON string processing method

JSON string processing method  
    function Jsonstr () {  
        $.ajax ({  
            URL: "Jsonstr",  
            dataType: "JSON",  
            success:function (data) {  
                $ ("#username"). Val (data.name);  
                $ ("#id"). Val (data.id);  
            }  
        });  
      
 
3 jquery, we do not need to go to new XMLHttpRequest (), and do not have to focus on compatibility issues between browsers, here jquery has been handled for us, the byte using $.ajax can be, in the callback function, old-fashioned writing, you need to write:

Xhr.onreadystatechange = function (data) {  
         if (xhr.readystate = = 4 && Xhr.status = =) {  
                ...
            }
But in the notation of JQuery, a success:function (data) {...} Yes, it's a lot easier. Attach an old-fashioned Ajax request code
function Jsonstr () {  
    /** old notation 
        var xhr = new XMLHttpRequest (); 
        Xhr.open ("Get", "jsonstr"); 
        Xhr.onreadystatechange = function (data) { 
            if (xhr.readystate = = 4 && Xhr.status = =) { 
                //Convert JSON string to JS On object 
                var obj = eval ("(" + Data.target.responseText + ")"); 
                document.getElementById ("username"). Value = Obj.name; 
                document.getElementById ("id"). value = obj.id; 
            } 
        }; 
        Xhr.send (null); 
    *  
        /$.ajax ({  
            URL: "Jsonstr",  
            dataType: "JSON",  
            success:function (data) {  
                $ ("#username"). Val (data.name);  
                $ ("#id"). Val (data.id);  
            }  
        });  
      
 
Turn: The Ajax of the first knowledge of jquery