I’m using the recommendations laid down here (http://www.odetocode.com/articles/473.aspx) to write a JavaScript AJAX webchat system using simulated Namespacing and prototyping.
In one of my prototype methods I’m calling the $.ajax method in jQuery. What I then want to do is pass the returned JSON data into a method inside my JavaScript webchat namespace.
The problem seems to be because I’ve created an instance of my JavaScript webchat, I can’t directly call a method inside it because I need to address it through the instance.
The key part in the code below is
success: function(data, textStatus) { this.GetUpdate_Success(data) }, I’m thinking because we’re inside the $.ajax() method, that this no longer refers to our WebchatV3 object.
The full JavaScript code is shown below:
/// <reference path='/JavaScript/jquery-1.3.2-vsdoc2.js' /> // Simulated 'namespace' var AvonAndSomerset = {} // Chatroom run time data AvonAndSomerset.WebchatV3 = function(memberId, passcode) { this.Members = new Array(); // Members in the chatroom this.Questions = new Array(); // The questions queue in the chatroom // Details about the current user this.currentMember = new AvonAndSomerset.WebchatV3.Member(memberId, passcode, null, null, null, null, null); // Set-up AJAX defaults $.ajaxSetup({ type: 'POST', contentType: 'application/json; charset=utf-8', dataType: 'json' }); } AvonAndSomerset.WebchatV3.prototype = { // Get latest Member,Quetsion,Transcript and Room data from server GetUpdate: function(StartUp) { $.ajax({ url: 'JSON.aspx/Members_GetChanges', data: '{ MemberID: ' + this.currentMember.memberId + ', Passcode: \'' + this.currentMember.passcode + '\', ReturnAll: ' + StartUp + ' }', success: function(data, textStatus) { this.GetUpdate_Success(data) }, error: function(result) { alert('Members_GetChanges() failed: ' + result.responseText); } }); }, // Callback - on success of GetUpdate() GetUpdate_Success: function(data) { alert('The AJAX call was successful!'); }, // Does the MemberID exist in the local array? Members_DoesExist: function(MemberID) { alert('Searching for ' + MemberID); alert(this.Members.length); }
The easiest way to fix this is to create a variable that references
thisat the proper scope required.thisand scope work differently in javascript then most languages, in this case it is referring to the object being passed into the function.