Return JSON data synchronously using jQuery.ajax()

Written by stevey on September 10th, 2010

Normally, I would have used .getJSON(remotePageUrl,data,function(json){

//process JSON data here, for example

//if (json.length>0)






to get a JSON object returned from the remotePageUrl that processes my request asynchronously and send back a JSON format string like ‘{“Name”:”steve”,”ID”: “1234”}’

But today, I found out that the .getJSON() cannot be set to process data request synchronously. In order to send data to remotePageUrl and return result synchronously (reason for this was because I had a jQuery dialog to be populated with data returned from this call before the dialog was displayed; first I used $.getJSON(), the dialog showed up before the data was processed on server side and returned), I needed to use $.ajax(). Here is the ajax call that actually worked to serve my purpose well:


var dataUrl = “<%=root%>/ajax/AsyncEventDataHandler.aspx”;

var userid; var eventTypeId; var userEventDesc=”;

var responseText = $.ajax({

url: dataUrl,

type: ‘GET’,

dataType: ‘JSON’,

//dataType: ‘text’,

contentType: ‘application/json’,

data: “UserCalendarID=” + userCalendarID,

async: false,

success: function (response) {



var data=$.parseJSON(response);

userid = data.UserID;

eventTypeId = data.EventTypeID;

userEventDesc = data.UserEventDesc;





error: function (msg) { alert(“error: ” + msg); }



Here the response inside the function() is the same as $.ajax(….).responseText, and it should have a proper JSON string format or the jQuery.parseJSON() function will fail. The correct format example: ‘{“UserID”:”1211″,”EventTypeID”:”1″,”UserEventDesc”:”meeting”}’. I tried to put single quote around the field name and it did not go through $.parseJSON(). For example, this will not be parsed: “{‘UserID': ‘1211’,’EventTypeID':’1′,’UserEventDesc':’meeting’}”.

For that I attributed to this article at jQuery api site at: Otherwise, I would probably wasted more time in figuring out why the parsing was failing.



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