I am currenty trying to write my first ever stack exchange application and was using the SE Jaavascript SDK v 2.0 for this purpose.

I am stuck on the point of authenticating the user. I followed the steps mentioned here

I am able to complete the call to SE.init successfully, However, when I call SE.authenticate, I get a login window where-in I login using my StackExchange account. At this point, I get an error that says Unexpected domain on proxy URL.

I would like to point out that I am using a cloud-based IDE at nitrous.io and hence I can test-run this application within the preview URL provided by them. In my case, I access the preview URL as follows :

http://cybertron-nodejs-11139.apse1.actionbox.io:3000/files/index.html

Here is my code snippet for the JS file that contains all the initialization and authentication logic:

$(document).ready(function() {
  SE.init({clientId: 1880, 
    key: '396D79cbzmt3w*Pf)E7AUw((', 
    // Used for cross domain communication, it will be validated
    channelUrl: 'http://cybertron-nodejs-11139.apse1.actionbox.io:3000/files/blank.html',
    // Called when all initialization is finished
    complete: function(data) { 
        console.log(data)
        $('#login-button')
            .removeAttr('disabled')
            .text('Run Example With Version '+data.version); 
      }
  });
  
  $("#login-button").click(function() {
    
    SE.authenticate({
        success: function(data) { 
            alert(
                'User Authorized with account id = ' + 
                data.networkUsers[0].account_id + ', got access token = ' + 
                data.accessToken
            ); 
          },
        error: function(data) { 
            alert('An error occurred:\n' + data.errorName + '\n' + data.errorMessage); 
        },
        networkUsers: true
    });
  });