Ajax in Javascript implements foreground-to-background interaction

First case: The foreground incoming string parameter returns a JSON string, or a JSON array

The code is as follows :

Front desk:

$.ajax ({          URL: "Xxx/xxx.action",          data: "Id=xxx",          Cache:false,          async:false,          success:function ( Result)      {        A: The array returned by the receive backend is               var data = eval (result);        if (typeof (data) = "undefined" && data.length > 0)         {for        (var i=0;i<data.length;i++)        {        data[i]["id"];        data[i]["name"];        }        } B: The background returns the string, then the direct receive      },        error:function () {            alert ("Table loading error ...");        }      );
Background:

PrintWriter out = Servletactioncontext.getresponse (). getwriter ();/* Back JSON string * /

              
              
           
          
          
           Out.print (Jarray); Out.flush ();
         return null;

Second case: The foreground passes in the JSON array as parameters to interact with the background
Front desk:

function Delcheckeddata () {var array = new Array ();                 $ (": Checkbox[name= ' chk '][checked=true]"). each (function () {Array.push ({ID: $ (this). Val ()            }); }) if (Array.Length > 0) {var Gridjson = json.stringify (array, function (key, value) {Retu        RN value;        });        $.ajax ({url: "/xxx/xxx.action", Cache:false, Data: "idlistjson=" + Gridjson, Async:false,        Success:function (Result) {var instdata = eval (result);        corresponding processing}, Error:function () {alert ("error ...");            }        }); }} 
  background:  

Jsonarray Instarray = jsonarray.fromobject ("parameter");        for (int i = 0; i < instarray.size (); i++)        {            Jsonobject instj = (jsonobject) instarray.get (i);            String sId = instj.get ("id"). toString ();            Get the ID to do the appropriate action        }

Ajax in Javascript implements foreground-to-background interaction